Now on with the show. :)
Let me say right off the bat that I loved it. I really, really loved it. There aren't as many quote-for-all-eternity-and-still-laugh-a
Bias Alert: For anyone who doesn't realize this (and I'm not sure there are many people left in the world who don't) I am a huge, HUGE Ron fangirl. Just so you know. However, I think I'm able to step back from that a bit and see what would be the right way to characterize him in the films.
I went into GoF having seen many of the clips available online, including the one of Ron and Harry arguing the night Harry is chosen as a champion. That clip definitely gave me hope that Ron wouldn't be squashed under comic relief like I felt he was in the first three films. Once I saw the full scene in the movie... it only gets better. Not only does Ron get his fare share of lines and exposition, but he isn't demeaned and made to be the villain in the Ron/Harry schism. Rupert's acting is flawless throughout the fight. He's the epitome of Ron, thick-headed and a bit thoughtless, but also genuinely hurt and with some reason, and ultimately with his heart in the right place. What I loved about it was that, true to the book, both boys act hard headed and both are seen as sympathetic characters.
Also finally given his proper dues is Neville. Frankly put, Neville is the real star of the movie. He ROX the show, and is shown as such a courageous, sympathetic character, that you can't help but love him. Especially great is when Moody crucios the spider and Neville's reaction to it. Things are also changed around so that Moody's plan works and Harry does get the Gillyweed from Neville. It's a change that works well, because it cuts a lot of extraneous plot in a very effective manner. It also leads to one of the single greatest lines in all of moviedom, which I refuse to spoil here, because there's spoilers and there's spoiling, and that's something you should see for yourself. I will tell you that we get a very dorky but loveable Neville who is found practicing dancing by himself in the dormroom, and then later becomes one of the only people who actually enjoys himself at the ball. We also finally see his skill in herbology highlighted, granted by Bart Crouch Jr., but it's still made very clear that the boy has talent after all. We've finally got canon Neville, and he is awesome.
The only characterization I think they really pulled a Faramir on was Barty Crouch Jr., though it didn't hurt his characterization so much as Mr. Crouch's. In the film there is never any doubt over Barty's guilt, which takes away the idea of Mr. Crouch (and the ministry) sending his son to Azkaban on dubious grounds. It's made clear that the ministry is slightly slimy anyway, but Mr. Crouch doesn't seem like as much of a git in the movie as he is in canon.
Moving on to ships. I was truthfully surprised at the lack of trio-ship drama. I suppose I had been built up by all the talk and drama pre-movie, but when I finally saw it it just didn't seem like that big a deal in the overall scheme of things, which is funny because a large part of the middle of the movie is focused on romance. Harry and Hermione will not find the clear proof of their ship that many of the more... vehement seem to be looking for. Yes, there are hugs, yes, there is tender and sweet Harry and Hermione interaction, in fact, Hermione kisses Harry. (Stop right now, I can hear the groans from here. It's sweet.) But they are not constantly giving each other steamy, UST-filled looks as the promo pictures might lead one to believe.
On the other side of the equation, a lot of the more anvilly ;) R/Hr moments were left out, which is one thing I was sad about. (My inner shipper really wishes there had been a lost arm of a Mini-Krum doll.) But overall I thought there were a lot fewer trio shippy moments than I thought there would be. And I definitely didn't see any sign of a dramatic and angst-filled love triangle between them, a very, very good thing. Thinking about it now, I think my impression stems from the fact that I didn't see a lot of Ron jealousy of anyone for romantic reasons. I didn't notice any Krum-hating happening, nor any jealously towards Harry about the rumors of him dating Hermione. Granted these two things happened in canon, but I'm willing to (grudgingly) accept their absence from the movie because I think it would have been hard to stick them in a two hour flick without overly hurting Ron's character. Don't worry, though, the Yule Brawl is still very much intact, although it takes place in the entranceway rather than the Gryffindor common room. Emma plays the Yule ball very well, as does Rupert. The horrid dress is... well, it's still horrid, no way around it, but the set-up of Hermione's entrance makes it work well, despite the dress. And there is something of a noticeable difference in her appearance, though not as much as canon, I suspect.
The Harry/Cho relationship was also great. Harry is far more dorky in this film, especially in regards to Cho. The "wannagoballwime" scene is perfectly canon and hilarious. Cho is played perfectly. There is also (much to my delight) a lot more Ginny in this film. She is everywhere. Whenever there's a shot she could reasonably be in, there she is, in the background. She even gets one good line in about Ron's dress robes, more than can be said about other characters who play a minor role in the book. It's clear they're setting up for the H/G relationship in HBP, which is fine by me.
There is also another lovely Harry ship in the filmy, namely unrequited Myrtle/Harry. It is HILARIOUS! She MOLESTS HIM! There is much ghost on boy action. At one point, I'm fairly sure she is actually STARING AT HIS CROTCH. Along with this delightful ship, you should also keep a keen eye open for Ron/Krum, McGonagal/Snape, Filch/Mrs. Norris, and much more.
The movie ends with a absolutely lovely trio-friendship moment, which I loved. Honestly, despite all the dating and teen-drama going on, and all the hype WB has given the Yule Ball, the thematic focus was far more on friendship than romantic love.
Goblet of Fire has gotten a lot of things right, and it has fixed a lot of the problems I saw in the earlier films. The characterizations are finally, mercifully, right. Ron and Neville are very well done by, and that is an amazing thing to see. There is also far less line stealing going on, though I haven't read GoF recently so I could be underestimating. Overall the plot is definitely changed a lot. Scenes aren't just cut, they're also rewritten, combined with other scenes, and entire plot points are changed completely. However, all of this works well towards keeping the movie spiritually accurate and contributes to a better made film overall. There aren't any plot holes to be seen in this movie, and it fits into its timeframe without feeling choppy or overly rushed. It's missing some of the flair and originality that Prisoner of Azkaban had, but it's solid plotting, wonderful characterization, strong themes, and gut-wrenching ending (which will absolutely destroy you even if you know perfectly well what's coming) combine to make it a better movie and, in my opinion, the best of the films so far.