As a guitarist/percussionist who had piano lessons as a kid (and hated them) I have always been a little intimidated by the piano. Toward my goal of being able to comp and improvise over changes, I have purchased several jazz piano method books, including titles by Jerry Coker and Dan Haerle, and they have all been helpful.
Mark Levine's book, however, is exceptional. He introduces his concepts in perfect-sized chapters, with musical examples bracketed by coherent and engaging explanations. There are dozens of very musical exercises, and lists of suggested jazz standards for applying them. He conveys the essential elements of jazz theory in an easy-to-digest but highly intelligent anecdotal writing style.
The pacing of how material is presented in a method book is very important to the advancing musician. For example, I always knew that the melodic minor scale was important, but it only fully came together in my head when I worked through Mark's chapters on scale theory. Instead of being bombarded with chord voicing options, there are two or three. The emphasis is on getting you prepared enough to play music! Helpful hints seem to appear just as you need them, and Mark's enthusiasm for the piano provides subtle encouragement for the exhausting but rewarding process of learning jazz.
This is a book which stays on my music stand. It's large but spiral-bound. The font size is just right, and notes are professionally typeset (I hate books where you spend half your time deciphering notes from the author's scrawl). Bonus points for the great photos and the recommended discographies from all periods of jazz.
I would recommend this book to any intermediate to advanced player looking to expand and strengthen his or her abilities to comp and solo on piano. No one book can teach you everything, but this one is a hell of a start.