I haven't read the book, but I did just see the movie.
If you're in to Zombie movies, this doesn't count. It's much more to do with Robert Neville's deteriorating mental state and I think Will Smith did a pretty good job of it although I can't help but feel that someone was holding Will Smith or the director back from making it as dark as it should have been.
I have a couple of non-plot related gripes.
1) Will Smith, or his agent, or the director, just had to put this sappy foreshadowing in there. By that I mean: the butterfly:
2) I think they used the same CGI animation house as in I, Robot, I say this because I'm pretty sure they used the same models, if not the same sequences, but with different skins.