Often cited work about the development of Heidegger's thought. It has several good bits, like an lengthy explanation on why he wasn't able to finish Sein und Zeit (Being and Time) as originally planned. It is quite thorough and written in a rather detached style, i.e. it is about Heidegger, not 'thinking along', which has its pros and cons.
The work is published in 1963 and in the afterword from 20 years later Pöggeler highlights some of the work's faults. There is not really one straight development ('path') of his thought, but there are multiple paths. It is missing his last thoughts of the sixties, and, probably most importantly, it completely ignored Heidegger political engagement with the Nazis. Finally, Pöggeler had consulted Heidegger himself, who (intentional or not) turned out not to be the most reliable source. This also explains why some sections (esp. about Erörterung) don't seem to be based on any published works.
It would have been nice if Pöggeler had been able to rework the book to address these issues instead of just adding this afterword.
This is an authoritative and compelling introduction to Martin Heidegger's body of work. I especially valued this book for its discussion of the logic of silence, Sigetik, in virtue of which Heidegger proposes we explore Being at greater depth than the merely conventional logic of discourse. Poetry can tap into this rich eloquence beyond normal speech, and "name what is holy." Instead of a chain of explanations, operating on a superficial level, by embrace the Ab-Grund of Being, i.e. the abyss.