<< *warning* spoilers if you haven't seen the film.
Anyway.... I thought the beginning was pretty good, but most of the film after he met Jude Law was pretty dumb IMO (and I like pretty much every movie Jude Law is in). I didn't understand why Jude stuck with the kid for so long, among many other things. The plot got pretty predictable for awhile, however the film totally goes into uncharted territory once he meets the "blue fairy". I liked the whole "aliens trying to understand mankind" thing that was going on there, but the "we can clone someone, but only for a day" concept doesn't make any sense, especially by today's standards. Perhaps 10+ years ago (when Kubrick was toiling with how to make the film) it made more sense, but with our modern knowledge of cloning, that idea is totally bogus. That basically ruined the movie for me. I liked some of the ideas in it, however.
I hope someone can understand my ranting, because I sure can't! >>
It wasn't cloning - they actually brought her back, not a copy of her. There's a big difference. Besides, that really has very little to do with the point of the movie. I agree that the movie would have been ok without the ending after the manhattan scene, but it works with the ending too...and not just to have a "happy" conclusion - it provided a means for him to "become human" through death. Spielberg's speech about that is pretty insightful.