In my opinion, Jenni Tennison's _Beginning XSLT_ is head and shoulders the best learning-XSLT book.  It was recommended to me by the folks at Mulberry (who bring you the Balisage conference every year; sign up now at http://balisage.net!), and was the one that finally got me past my blocks against understanding push-style XSLT (and I speak as someone who's done a lot of eager mostly-functional programming for years).

I have not read the XSLT 2.0 edition, which is probably why I don't know XSLT 2.0.

(No connection except as a delighted customer.)