yes, the illusion of life is a very informative book on animation - for the lacking how-to part, id say its best supplemented with richard willams' "the animators survival kit", which i bought for mere enjoyment and interest in animation technique. its amazing in that it opens your eyes not in the way johnston and thomas take you by the hand and take you on a behind-the-scenes tour of disney history, but to the more hands-on technical "form" of how animation works as a craft. both books together should be extensive, but also chock-full of enough animation knowledge to keep everyone with a bit of interest in the matter occupied for quite some time.

i agree with brainrust - there is a lot of carryover into illustration. walt stanchfields two volumes on gesture drawing come in handy there, too.