Short, non-spoiler version: it's pretty, but it doesn't seem like it's a peer to the previous two.
Spider-Man 3. Sequel to two of the greatest superhero movies ever created. None of the major elements have changed for this movie -- the same director, script writers, actors, production team, visual effects crew, and so forth have all returned. It seems like it's a slam-dunk waiting to happen.
But it doesn't. Instead, it seems like...well, let me rewind a bit.
Early on in the production process, Sam Raimi (director) made it pretty clear that he didn't like the character of Venom. That's fine -- personally, I really like the character of Venom, in much the same way that I really like the character of Apocalypse: as a concept that has historically been poorly executed. However, after significant convincing on the part of Avi Arad (Marvel's lead movie producer type), Raimi apparently found something in Venom that he liked -- a direct foil for Spider-Man. That is, of course, the best way to implement Venom; as Spider-Man's opposite.
However, trouble was clearly on the horizon with this movie from the outset: Raimi was going to deal with Peter both getting and shirking the (alien) black suit, tie up the trilogy-arced story of Harry Osborne, and -- oh yeah -- also introduce both Sandman and Venom. Something had to give. And it did. But what bugs me is that it seems like it gave intentionally.
Spider-Man and Spider-Man 2 both received exceptionally high Rotten Tomatoes ratings (in the 90s). Spider-Man 3, as of this writing, is at 65 -- a 25 point drop compared to its predecessors. And, honestly, it does feel deserved. Spider-Man 3 is not the equal or peer of the other two.
It's the strong feeling of a friend of mine (who is an avid fan of Raimi) that the movie's drop in quality -- and, also, its flat-out absurd handling of the black costume and Venom -- was intentional: Raimi is flat-out assaulting clamoring Venom fans and studio execs alike with, "You want the black suit? You want Venom? HERE YOU GO! ENJOY!" Consequently, the story of the movie comes off as excessively spiteful -- not in that the story possesses elements of spite, but that it's trying to spite the audience.
The movie does have strong moments. For as small a part as he ultimately played, Sandman's story was quite good, and even touching. Had it been given a chance to be more, it could have been truly moving. Further, though I don't think James Franco handles being the Goblin as well as Willem Dafoe did, he makes an admirable effort, and there are moments where he truly, truly embraces a vile wickedness, and the audience can do nothing but cackle with shared glee at his torment of our beloved protagonist...that is, when our beloved protagonist isn't making a complete fool of himself with his Fall Out Boy outfit and haircut.
The end battle ultimately feels like it was ripped away from us. It's grandiose and epic...until it suddenly ends through what amounts to fiat. It's as if Raimi decided it was time to end the movie, so he suddenly does. There's no satisfaction in the resolution.
Worst of all, though, is that so much of what had gone on in the previous two movies could have easily been used as set-up for this one. We were introduced to J.J. Jameson's son in the previous movie -- an astronaut. Indeed, in the cartoon, the crash of Col. Jameson's space shuttle mission, narrowly averted by Spider-Man, is what returns the symbiote to Earth. In the movie, it simply arrives on a meteor that silently -- SILENTLY -- strikes the ground very near a web-suspended Peter and MJ as they nuzzle one another.
Further, the implementation of Eddie Brock simply doesn't work. The reason Venom works so well as a foil for Spider-Man is that Brock is Parker's opposite -- he is the brawn to Parker's brain. Consequently, Spider-Man must rely on his wits to defeat the significantly more powerful Venom. However, in this, Venom seems more powerful only by virtue of the fact that he's angrier, meaner, and Spider-Man can't sense him. Beyond that, he doesn't seem significantly threatening.
A few things were done right in this movie, and they really ring true when you see them. But a lot of them -- and particularly everything concerning the central plot element of the black suit, and its natural child element of Venom -- are handled with what can only be described as deliberate bad taste. Raimi's movies have been shown to be capable of inspiring awe, and he's also shown himself a capable director of horror-camp. He now demonstrates a new talent: spiteful hero-camp.
One silver lining exists, however, in that Doctor Connors is shown analyzing a piece of the symbiote that Parker gives him. He sees that the symbiote bonds to DNA and gains the features of its host. This may be foreshadowing at the rise of the Lizard in Spider-Man 4, though whether Raimi will return -- and whether or not we'll be happy with him doing so -- remains to be seen.