It wasn't bad, but I didn't like the casting of Peter Parker - he had too much of a "hurt puppydog" look about him throughout the movie. Now, granted, he's *supposed* to be an angst-filled teenager trying to reconcile super (well, extraordinary) powers, and they carried out the major parts of the storyline of his initial reactions to his powers pretty much along similar lines as the comics, although of course some of the parts differed because of the media it was being presented with, but I didn't think he really convincingly carried out his attempts to woo Mary Jane - he was too ineffective. And, well, Peter Parker's face is just too cute (IMO). :=)
There were a couple of changes to his powers that may have effects in any sequels (for instance, in the comics one plot device that comes up every so often is him running out of his spider goop for the device he's invented to shoot webs, where in the movie it's an innate power), but I thought the Spiderman parts of the movie were pretty good, and the casting and acting of the Green Goblin was also pretty good. If you see still shots of him swinging along New York streets they may look goofy, but the film's CGI carries it off pretty well.
Besides the film, a brief moment of excitement occurred in the theater when the fire alarm went off. The problem was I didn't know what the heck it was - didn't sound like any fire alarm I've heard in other buildings before. Eventually as people started filing out I figured out what it was, but it's one thing to falsely yell fire in a theater, and other to have an unrecognizable alarm.