The Keys to the Kingdom: The Rise of Michael Eisner and the Fall of Everybody Else by Kim Masters.
The Magic Kingdom: Walt Disney and the American Way of Life by Steven Watts is also another good book, and probably my favorite biography of Walt.
These are both must reads for anyone who wants insight into the company and the men behind it.
I will say that Masters didn't always have her facts correct in the book (sometimes on simple things), but it still is a great read. I often thought about asking Michael to sign my copy (more as a joke) but was afraid I might see his temper, which I never personally witnessed.