Four kinds of question are given at A. i, 197: ‘declarable ( = decidable) unilaterally (by empirical verification), declarable after analysis, declarable through a counter-question, and unanswerable’. “Is life suffering?” seems to belong to the category which has to be analyzed first. The example of answering unilaterally what should be analyzed you can find in MN 136: "Though the wanderer Potaliputta’s question should have been analysed before being answered, this misguided man Samiddhi answered it one-sidedly.”
Suttas recognise three kinds of suffering: the suffering due to pain, the suffering due to determintions, the suffering due to change. SN 38: 14
Taking stand on the first kind of suffering, life cannot be described as suffering since it is obviously not only mixture of pain and pleasure, unpleasant mental states and happiness, but also being born as a human is considered as a happy destination. But this is valid only on the very gross level, it is common man knowledge.
The first noble truth says: … in short, the five aggregates affected by clinging are suffering. This is called suffering. MN 9
pañc’upādānakkhandha is defined elsewhere as person (sakkaya) or burden (bhārahāra):
“Lady, ‘,person, person’ is said. What is called person by the Blessed One?”“Friend Visākha, these five aggregates affected by clinging are called person by the Blessed One. MN 44
“And what, bhikkhus, is the burden? It should be said: the five aggregates subject to clinging. … And what, bhikkhus, is the carrier of the burden? It should be said: the individual (puggala), this venerable one of such a name and clan. SN 22: 22
[When we decided to translate sakkaya as person which is connected with sakkayaditthi and so obviously with ignorance, puggala has to be render as individual, impermanent set of aggregates, but not necessarily connected with ignorance, as in the case of arahat. Suttas recognise 9 kind of individuals (puggala) 8 ariyas and puthujjana.]
Since the common man sees himself as a person (sakkaya) his very being (bhava) can be render as suffering. In this sense his life is suffering, no matter how happy he feels himself, but since we are dealing here with the first noble truth, it is the suffering he doesn’t know about. But puggala carrying the burden of personality can realise nibbana now and here, namely cessation of being:
“The reason why the Tathāgata is not to be found (even here and now) is that he is rūpa-, vedanā-, saññā-, sankhāra-, and viññāna-sankhāya vimutto (ibid. 1 <S.iv,378-9>), i.e. free from reckoning as matter, feeling, perception, determinations, or consciousness. This is precisely not the case with the puthujjana, who, in this sense, actually and in truth is to be found.” (Nanavira)
So we have puggala without personality, “who” still walks, eats, experiences agreeable and disagreeable, but is totally free from any kind of mental suffering, especially suffering due to determintions. For dialectic puggala - individual/ sakkaya - person see Absolute Truth by Nanavira, or just use Google for “multiple personality disorder”, there are registered cases of one individual (puggala) with more than one personality (sakkaya) . Of course unlike modern medicine, in Dhamma, an individual with one personality is the case of serious mental disorder. Nevertheless studying the case of multiple personality disorder can help to see difference between puggala and sakkaya.
Some useful insights on suffering due to determintions from Nanavira:
But now you say, ‘If all things are characterized by dukkha….’ This needs careful qualification. In the first place, the universal dukkha you refer to here is obviously not the dukkha of rheumatism or a toothache, which is by no means universal. It is, rather, the sankhāra-dukkha (the unpleasure or suffering connected with determinations) of this Sutta passage:
There are, monk, three feelings stated by me: sukha feeling, dukkha feeling, neither-dukkha-nor-sukha feeling. These three feelings have been stated by me. But this, monk, has been stated by me: whatever is felt, that counts as dukkha. But that, monk, was said by me with reference just to the impermanence of determinations…. (Vedanà Samy . 11: iv,216)
But what is this dukkha that is bound up with impermanence? It is the implicit taking as pleasantly-permanent (perhaps ‘eternal’ would be better) of what actually is impermanent. And things are implicitly taken as pleasantly-permanent (or eternal) when they are taken (in one way or another) as ‘I’ or ‘mine’ (since, as you rightly imply, ideas of subjectivity are associated with ideas of immortality). And the puthujjana takes all things in this way. So, for the puthujjana, all things are (sankhāra-)dukkha. How then—and this seems to be the crux of your argument—how then does the puthujjana see or know (or adjudge) that ‘all things are dukkha’ unless there is some background (or criterion or norm) of non-dukkha (i.e. of sukha) against which all things stand out as dukkha? The answer is quite simple: he does not see or know (or adjudge) that ‘all things are dukkha’. The puthujjana has no criterion or norm for making any such judgement, and so he does not make it.
The puthujjana’s experience is (sankhāra-)dukkha from top to bottom, and the consequence is that he has no way of knowing dukkha for himself; for however much he ‘steps back’ from himself in a reflexive effort he still takes dukkha with him. (I have discussed this question in terms of avijjā (‘nescience’) in A Note on Pañiccasamuppàda §§23 & 25, where I show that avijjà, which is dukkhe aññānam (‘non-knowledge of dukkha’), has a hierarchical structure and breeds only itself.) The whole point is that the puthujjana’s non-knowledge of dukkha is the dukkha that he has non-knowledge of; and this dukkha that is at the same time non-knowledge of dukkha is the puthujjana’s (mistaken) acceptance of what seems to be a ‘self’ or ‘subject’ or ‘ego’ at its face value (as nicca/sukha/attà, ‘permanent/ pleasant/self’).
And how, then, does knowledge of dukkha come about? How it is with a Buddha I can’t say (though it seems from the Suttas to be a matter of prodigiously intelligent trial-by-error over a long period); but in others it comes about by their hearing (as puthujjanas) the Buddha’s Teaching, which goes against their whole way of thinking. They accept out of trust (saddhà) this teaching of anicca/dukkha/anattà; and it is this that, being accepted, becomes the criterion or norm with reference to which they eventually come to see for themselves that all things are dukkha—for the puthujjana. But in seeing this they cease to be puthujjanas and, to the extent that they cease to be puthujjanas, to that extent (sankhāra-)dukkha ceases, and to that extent also they have in all their experience a ‘built-in’ criterion or norm by reference to which they make further progress. (The sekha—no longer a puthujjana but not yet an arahat—has a kind of ‘double vision’, one part un-regenerate, the other regenerate.) As soon as one becomes a sotà-panna one is possessed of aparapaccayā ñānam or ‘knowledge that does not depend upon anyone else’: this knowledge is also said to be ‘not shared by puthujjanas’, and the man who has it has (except for accelerating his progress) no further need to hear the Teaching—in a sense he is (in part) that Teaching.
So far, then, from its being a Subject (immortal soul) that judges ‘all things are dukkha’ with reference to an objective sukha, it is only with subsidence of (ideas of) subjectivity that there appears an (objective) sukha with reference to which the judgement ‘all things are dukkha (for the commoner)’ becomes possible at all. L 145
Or
And where does the Buddha’s Teaching come in? If we understand the ‘eternal’ (which for Kierkegaard is ultimately God—i.e. the soul that is part of God) as the ‘subject’ or ‘self’, and ‘that which becomes’ as the quite evidently impermanent ‘objects’ in the world (which is also K.’s meaning), the position becomes clear. What we call the ‘self’ is a certain characteristic of all experience, that seems to be eternal. It is quite obvious that for all men the reality and permanence of their selves, ‘I’, is taken absolutely for granted; and the discrepancy that K. speaks of is simply that between my ‘self’ (which I automatically presume to be permanent) and the only too manifestly impermanent ‘things’ in the world that ‘I’ strive to possess. The eternal ‘subject’ strives to possess the temporal ‘object’, and the situation is at once both comic and tragic—comic, because something temporal cannot be possessed eternally, and tragic, because the eternal cannot desist from making the futile attempt to possess the temporal eternally . This tragi-comedy is suffering (dukkha) in its profoundest sense. And it is release from this that the Buddha teaches. How? By pointing out that, contrary to our natural assumption (which supposes that the subject ‘I’ would still continue to exist even if there were no objects at all), the existence of the subject depends upon the existence of the object; and since the object is manifestly impermanent, the subject must be no less so. And once the presumed-eternal subject is seen to be no less temporal than the object, the discrepancy between the eternal and the temporal disappears (in four stages—sotāpatti, sakadāgāmitā, anāgāmitā, and arahatta); and with the disappearance of the discrepancy the two categories of ‘tragic’ and ‘comic’ also disappear. The arahat neither laughs nor weeps; and that is the end of suffering (except, of course, for bodily pain, which only ceases when the body finally breaks up). L 27
So if we take our stand on suffering due to determintions statement life is suffering is true for puthujjana but not for the arahat, since with cessation of being now and here suffering or pañc’upādānakkhandha is removed from experience.
Finally suffering due to change: while in commentaries it is explained as follows:(viparināmadukkhtā̄) is pleasant feeling, which brings suffering when it comes to an end; we can also take our stand on MN 115:
There are, Ānanda, these two elements: the conditioned element and the unconditioned element.
“There are three determined characteristics of what is determined: arising is evident, fall is evident, and alteration of what is present is evident. There are three undetermined characteristics of what is undetermined: no arising is evident, no fall is evident, and no alteration of what is present is evident.”
A. 3:47
Taking our stand on dialectic sankhata/ asankhata, since any experience whatever is temporal no matter whether puggala carries the burden of personality (sakkaya) or as in the case of arahat is free from it, any experience whatever, is suffering so in this sense life is suffering but not because we experience suffering, but rather we suffer experience. And so even the highest rebirth (compare to unborn) cannot be recommended.
Leopardi asks:
Are we born, then, only to feel what happiness it would be had we not been born?
It seems it is exactly the task given us by the Buddha in the Four Noble Truths. However no matter how accurate are our observations of the painful nature of life, without faith certain amount of suffering simply escapes from our vision, which obviously might influence negatively our practice.
Lichtenberg: To live when you do not want to is dreadful, but it would be even more terrible to be immortal when you don’t want to be. As things are, however, the whole ghastly burden is suspended from me by a thread which I can cut in two with a penny-knife.
Nanavira Thera:
The Trial describes what happens to a man when he starts to think: sooner or later he condemns himself as unjustified, and then despair begins (K.’s execution, the execution of hope, is the beginning of despair—henceforth he is a dead man, like Connolly and Camus and so many other intelligent Europeans, and do what he may he can never quite forget it). It is only at this point that the Buddha’s Teaching begins to be intelligible. But it must be remembered that for Connolly and the others, death at the end of this life is the final death, and the hell of despair in which they live will come to an end in a few years’ time—why, then, should they give up their distractions, when, if things get too bad, a bullet through their brain is enough? It is only when one understands that death at the end of this life is not the final end, that to follow the Buddha’s Teaching is seen to be not a mere matter of choice but a matter of necessity. Europe does not know what it really means to despair. L 71