Spider-man 3 is getting mixed reviews. I will see it no matter what since my sons are dying to go, but I felt that Sony might be making a mistake by having him confront numerous enemies in one movie as this seems to be what killed the first go-around of Batman sequels.
The original Batman had only the Joker and the first 2 Spider-man movies had one villain each, in the Green Goblin and Doc Ock. I think it becomes difficult to maintain focus in a movie and to develop the bad guy characters when you have multiple villains. Superman on the other hand has the problem of almost always having Luthor as a villain, which has happened in four out of the five Superman movies. The other had Richard Pryor--bleeh! Warner needs to pit Superman against Doomsday or Darkseid so that everyone can see just how much better Superman has gotten in the last 20 years.
The last Batman movie, Batman Begins, had things just about right. It introduced one villain, Ras al Ghul, while most of the focus was on another villain Scarecrow, but it was refreshing because there was no Joker, or Penguin or Mr. Freeze or Catwoman or any of the other hacknyed criminals of Batman history.