Quick and dirty: If you've seen the other 3 films, this one is much better. I give Mike Newel a lot of credit. There is a lot of material to cover and he did it very well (I'll touch on that later). Great start to what looks like an excellent few weeks of movies.
The Goblet of Fire is my favorite of the series thus far. It really the evolution of the series from children's novels to young adult. The movie portrays this very well. Newel deviates from the novel in a few places, but I believe it comes across on the screen as necessary for a film adaptation. The movie skips over Winky, who was a pivotal character in the novel. The "mystery" surrounding the house elf was too much ambiguity for the screen, which makes sense. All and all, I think you'll enjoy this one.
There are a few that left me very curious. The movie doesn't wrap up all the loose ends of the book. I don't want to spoil them, but when you see it (and look back on the novel), you will see there are actually quite a few things left unsaid, undone, etc. I don't know how the next movie can pick up after this one, because it will basically have to start with tying up the loose ends of this film. It will be interesting to see how it will be done.
Finally, there is one last thing I would like to touch on. Pacing.
The movie versions of these books have been tough because there is a lot of "necessary" content that needs to be explained to the viewer. There are not many things like what Peter Jackson did with Fellowship with Tom Bombidill. Peter had the luxury of not having to translate that part of the story to the screen because it wasn't necessary. There are not many things like that in the Harry Potter series. I do wish they had taken a full 3 hours to tell the story and include a 10 minute intermission. 2.5 hours just didn't seem like enough.