Heidegger has been accused of being many of the above things, including mystic, psychotic, and poet, and sometimes even a philosopher. Some of us like to think of him as all of the above. But there is a pervasive trend in particularly modern philosophy that would like to bracket out such things proper subjects for philosophy. For example, many Anglo-American analytic philosophers tend to think Heidegger is simply sloppy, perhaps a charlatan, but certainly not a philosopher in any traditional sense, and perhaps they have a point. Heidegger would have been the first to admit he was no philosopher in the regular sense, as a matter of fact he often disdained that sort of thinking. One could say that the divide between continental and analytic thought comes down to what one does with Heidegger (and it's for this reason that a thinker like Richard Rorty is so vexing for nearly everyone, since he is made of equal parts Heidegger, Wittgenstein, and Dewey).
Another way to examine this divide is to think about whether you take your philosophy as poetry, or as science (not to speak about poetic science or scientific poetry). Admittedly, this is an arbitrary and even false dualism, but as a heuristic device is can be helpful for getting one's mind around the later Heidegger, and for me, "Poetry, Language, Thought" is the best collection of the finest work of his "post-turn" period. The thing is a curious mix of philosophical poetry and prose-poems; they are literary tone poems, like those of Liszt and Strauss, and contain every color of Heidegger's complex thought. Every essay here is, I tend to think, the philosophy he always wanted to write, and the magnum opus of his later period, the Beitrýge (translated with mixed success by Emad and Maly, 1999), is a full blown exposition in aphoristic form of the thought concealed in PLT. That's my reading, of course, but I am more and more convinced that it is close to the truth of Heidegger's whole project of his later years.
There is not one essay here that doesn't belong. Several of them are almost legendary in their importance to Heidegger studies; for example, "The Thing" introduced Das Ding fully into Heidegger's thought, and "On the Origin of the Work of Art," easily the most stunning of the performances in this volume, contains his famous Zen-like phenomenology of Van Gogh's "Peasant Shoes" that can almost bring Heidegger's most devout follwers to tears. Perhaps this is a bit much, but it is beyond question, at least to my mind, that Heidegger came closer to "telling the best," as Whitman wrote, in these essays than he did at any other time in his career . "What are Poets For?" is the most nuanced single discussion of Hýlderlin in Heidegger's corpus, and Hýlderlin (as everyone ought to know) is Heidegger's patron poet. "Language" is as successful in 20-odd pages as Wittgenstein's Philosophical Investigations is in 230: favorable comparisons between the two greatest thinkers of the 20th century aren't nearly as common as one might expect. And on and on.
