An oldie but a goodie. Just re-reading it now, twenty years after my college ethics class. Some very good stuff in here; much needed in contemporary America, I'd say. Much more to him than just "he's one of those Utilitarian guys."
Vanity Fair (right) considered him "The Feminine Philosopher," and Punch (left) took its punches at him as well, because of Mill's feminist commitments. See The Subjection of Women for more, and check out On Representative Government for all those "quaint" notions we're currently trashing at warp speed.
Yes, he had his weak points, for sure: his defense of the Indian "Mutiny"(PDF) is a low point, as even such an admirer as Noam Chomsky has pointed out. And some of the themes developed in that article derive from On Liberty.
Oh, well. Mill would want you to think for yourself, anyway. That's the sign of a worthwhile thinker, in my book.
While we're speaking of books, a friend directed my attention to Mill's Autobiography, which I'm also reading. More good stuff from an honest man.