There are, as far as I know, three Foucault biographies available in English. I have read all of them. Eribon’s was the first to appear (I believe) but the least interesting. The Passions of Michel Foucault is the most gossipy (and it still doesn’t really give up that much dirt) and The Lives of Michel Foucault does a better job of giving you a sense of Foucalt’s place in theory/philosophy/whatever.
Eribon knew Foucault, apparently well, but that doesn’t come across in the book at all. What we get instead is a decent, but not the best biography of a man who in my opinion is one of the few French theorists whose work will stand the test of time.
Recommended for the enthusiast.