Well, you folks know how I feel about the film, but here's what a New Yorker thought of the movie, just in case you don't trust us sloooooow southerners... :) It really is magnificient!
I saw Iron Giant over a month ago at a Warner Screening room in New York, and unlike the print you saw, there was no pencil animation or signs of anything incomplete. Maybe this means they added stuff, which would be a mistake based on what I saw. But, I have to wholeheartedly agree on your opinion of the film. I left it with the same exact feeling I had when I left E.T. at the tender age of 6 or that last frame of Babe. It was incredible, you just had to smile. I've been shouting "Superman!" ever since.
I have to admit that initially I wasn't impressed by the animation, but the film kind of sucks you in and progressively the animation becomes invisible and you're just watching these characters and "living" the Iron Giant. The Superman planting in there, goddamit, there hasn't been writing like that in a long time. One thing about good animation, as television animation like King Of The Hill and The Simpsons has shown us, is that there is an intense appreciation and attention to the writing -- I suppose because there has to be -- which gives a film like this real strength and discipline. There's also some pilfered Simpson jokes in there, which was interesting to see.
Last thing, depending on whether it was temp music or not, but the music I heard seemed very final and worked perfectly. Particularly the Superman theme at the end, at which point I lost it. They should leave it just like that. It is without question the best film of the year.