Add me to the disapointed side. I think I probably cared for the GoF least of the four movies. The first two followed the letter of the books very well, but lost some of the spirit in doing so. PoA diverged from the books a fair amount, but their changes and additions "felt" more like Hogwarts and I thought they captured the spirit of the book. Meanwhile, Goblet of Fire didn't seem to follow the letter or the spirit of the books.
They hacked out massive chunks of the novel, and while I understand that they needed to trim it down, I think they underestimated their audience. Millions of 8 year olds have read this 750 page book a dozen times. You don't think they'd sit through a three hour movie? Or two 2 hour movies? I think they would.
IMO, most of the changes weren't very good, and many were pointless. Such as the very mechanical set up at the Quidditch World Cup, the fact they were in the nosebleeds instead of in the Top Box. The Moody twist went from being heart-breaking and shocking to dull and way too foreshadowed.
I've seen several people say that book 4 isn't a cheery and fun book to read. What the heck? Bour four was an awesomely fun read. Sure, Harry's miserable for several large chunks of it, and it's got the devastating ending (Mood's still by favorite DADA teacher, and he's the bad guy? Cedric's death, I liked Cedric, JK built him into a character with real heart in books 3 and 4. Voldemort's return), but most of the book is fun to read and imagine. The ball was great, the tasks were fun to read and watch. Meanwhile, in the movies, the dragon looked cool, but otherwise the 1st task looked kind of silly. The mage who just summoned his broom from a mile away can't easily get it from four feet away? The second task was pretty boring, and it cut out most of the interesting parts from the book. And the third task was utterly blah. The final task was a hedge maze that sometimes tries to eat you? WTF? That's their replacement for Giant Spiders, Blast Ended Skrewts, magical spells and a Sphinx?
All in all I felt they cut out too much, cut out many of the wrong things, dumbed down the story, plots, twists, and characterizations entirely too much. The above poster who thinks Neville got better play in this movie should see how much more he's gotten in the novels.
Don't get me wrong, there were good parts. Fred and George were hilarious. The scene where Harry asks Cho to the ball was perfect. The scene where Ginnie and Hermione help Ron back after he asks Fleur to the ball was perfect. Ron's "helping" Harry for the first task was funny. Neville was good, and Ginnie got a few more props. The Moody/Draco/ferret scene was hilarious.
Still, all in all, blah. Should've made it a mini-series.
Edit: And for those of you who haven't read the books, give them a chance, just read the first one. It's better than you think.