Short version: HULK SMASH!
Let's cut to the chase, shall we? If you're expecting a movie as fun and great as Iron Man, you're going to be disappointed. However if you're a big fan of the Hulk in the comics and/or in the old TV series and hated Ang Lee's version you are going to LOVE this movie.
As I sat and watched the opening credits, it occurred to me that the best way to describe The Incredible Hulk is to call it a semi-sequel to the last film. They actually did something very wise during the opening: Instead of taking up a significant portion of the film re-creating Bruce Banner's origin as the Hulk, it was done via a series of quick scenes during the opening credits. As soon as the credits are done, we're plunged right into Banner's present-day life on the run.
We find Dr. Bruce Banner (Ed Norton) living in less than stellar accommodations in Brazil. He's working a menial job in a soda factory and when he's not there he's learning martial arts and anger management from a Brazilian martial arts instructor. Banner is trying his best to lie low and amazingly, it's been five months since his last transformation into the Hulk.
Early on fans get nods to the old TV series that starred Bill Bixby and Lou Ferrigno, and yes, eventually even the music from the TV show is heard in the movie. There is cool stuff that fans will appreciate throughout the film.
It turns out that Bruce has been staying in touch with someone (via satellite uplink) who is trying to figure out how to cure him of his affliction. Banner's nemesis, General Ross (played very effectively by William Hurt), has not stopped looking for him and as expected gets a lead that allows him to send a special ops team after our hero. Leading the team is Emil Blonsky (Tim Roth), a long time military man who loves field ops and is determined to be in combat situations for as long as his body can handle it.
There's a very exciting chase scene where the team corners Banner and we see his first transformation very early on in the film. Now, a few words about the Hulk character in this movie - This is NOT Ang Lee's Hulk folks. Sure, that version got angry and threw tanks around, but overall he seemed kind of likable, and dare I say - huggable.
This Hulk is a very scary character.
Words that came to mind during his first appearance included: ferocious, brutal and savage.
Eventually Banner makes his way back to the U.S. and although he tries to avoid her, of course find his true love - Betty Ross (Liv Tyler), estranged daughter of the General. As you can imagine, she gets put in harms way and is not repulsed by the big, green angry version of good old Bruce. Meanwhile it doesn't take Ross much effort to convince Blonsky to participate in an experiment that will take 10 years off his life and make him - are you ready? - a super soldier.
By the end of the film he turns into the monstrous Abomination and the Hulk must battle him to save the city.
The Incredible Hulk, while it has a couple of lighthearted moments, is not a "fun" superhero movie. It's dark and gritty and has more in common with the tone of Batman Begins than it does with Iron Man. It's a very good movie, but it's not great in the sort of way that makes you want to go back and see it again unless you're a big fan of the character.
Ed Norton was excellent as Bruce Banner, I thought Liv Tyler did a decent job as Betty. I really enjoyed seeing William Hurt play a tightly wound General, he's aged since we've last seen him and he was a great fit for the role. Tim Roth also did a believable job during what few scenes he had with actual dialog.
If you are a big Hulk fan, this movie is going to be right up your alley. The Hulk is as ferocious and uncaring about collateral damage to people as he is in the comics, you've got multiple references to the old TV series, and a great cameo by Lou Ferrigno. In addition there are classic Hulk moments from the comics like him saying "HULK SMASH!," the mega-hand-thunderclap, hitting the ground so hard as to knock his opponent down, etc. Also the final battle is quite long and is filmed in such a manner that you can actually tell what's going on, as opposed to the hyper-cut/close-up fashion at the end of Transformers that I really hated.
And yes, Robert Downey Jr. appears during the film as Tony Stark (his appearance generated the biggest cheer of the movie at the screening I attended) and if you're a Marvel Comics fan, what he says will put you through the roof on the coolness meter. Marvel is most definitely weaving a thread through their superhero movies that will end up at Avengers Mansion.
Despite all the above, it just didn't scream "great" to me... more like "very good."
All in all, I'd say it's definitely worth checking out.