I think for one, the special fx are better, but that is a cause of the time period. I like Garfield better than Tobey, and I like the fact they make Parker more of a joker, which spiderman is.
I thought the end of 2 was setup well for the next one, and they did not try and spend a lot of time on all 3 villians (left open for later movie) and stuck with one main bad guy. Spiderman 3 with Venom, sandman and new goblin was a bit busy. I also hated the fact the goblin was just a mask...