I liked it a lot. Goblet of Fire is my favorite book of the series so far, so I was worried the movie wouldn't do it justice, but it does. The tasks are dangerous and dramatic, Volemort's return is plenty creepy and scary, and Cedric's death is appropriately tear-jerking. There's plenty of humor, too, which keeps it from being the dark, tense, and depressing experience it could have been. In particular, the scene in the prefect's bathroom is absolutely perfect.
Sure, a lot of stuff from the book got cut--it had to, or the movie would be a mini-series length. So there were no house elves, no Draco in the woods at the Quidditch World Cup (no one was in the woods, actually), no Ludo Bagman, no Percy or Mrs. Weasley, no mother for Cedric, no mention of Harry giving his tournament prize to the twins. There was also no quidditch played. I wrote the other day on a discussion board that there would be no quidditch in GoF--thinking of how the school season was cancelled due to the Tri-Wizard Tournament--and someone corrected me, saying that since the story opens at the Quidditch World Cup there would indeed be some--except there really wasn't. The teams flew into the stadium and next thing you know everyone's back in the tent after the match and not even discussing the action or outcome.
I'll be interested to see what people who didn't read the book make of Barty Crouch Jr. and Sr. The latter particularly gets short shrift as far as character development goes; it's never explained that Jr. was supposed to have died in Azkaban, and Mrs. Crouch isn't mentioned at all. I think some of the dialog and events in the film would be confusing without that background, but maybe not. Perhaps it's been long enough since Mr. Karen listened to the book that he can tell me if it makes sense to someone coming in to the movie cold.
Hermione's transformation for the Yule Ball is less striking than the one I imagined when I listened to the book--her normal everyday look in the movie is prettier than it should be, with her hair being nicely curly instead of bushy and frizzy, so she doesn't have that much room to look better than usual. Krumm was better looking than I would have expected based on the book, but it's the movies, so that's not surprising, and they didn't turn him into a pretty boy. That's Cedric's role, and he fulfills it quite nicely.
John Williams didn't do the music for this one--though his "Hedwig's Theme" does make an appearance. Perhaps some of this other themes were quoted as well, I wasn't paying that close attention to the music and haven't bought the soundtrack to this one yet (I've been making do with having the one from PoA on heavy rotation). I'm glad I didn't--if it includes the unfortunate pop tune that played over part of the end credits I might have been dreading that the whole time I was watching.
As usual, I stayed for all the credits. There's no cookie at the end like Chamber, but there is one amusing line inserted a little before the notice that no animals were harmed during the making of the film.
I am sure I will see it again--it's at the IMAX at the Henry Ford, so I'll probably try and catch it there. Someone on hp_knitting who saw it at an IMAX said it was great--she could count the stitches in the scarves. And there is a lot of knitwear to look at in this one--now that I'm a knitter (yes, I am calling myself that even though I barely know how to purl at this point) I found myself paying much more attention to the scarves and hats and sweaters. The Hufflepuff scarves feature a quite dark yellow now, and there's what appears to be a Hogwart's scarf with stripes of all the house colors on it that's new for the tournament. Also, the R on Ron's Weasley sweater looked appliqued on instead of being knitted in. I'm really wishing I'd brought my Ravenclaw scarf to work on this morning--traffic was light and I got to the theater much earlier than I'd planned--all that time I was waiting I could have been knitting. I guess a *real* knitter would have thought of that, huh?