Soarin' is the first to come to mind. It's not a question of overrated attractions, since every thing there is really pushed as being awesome in a way, but more or less of the attraction being a let down all together.
Kali River Rapids is one, when compared to Popeye. The Backlot tour when it was around, but to be fair, I don't think I ever rode it pre 2006. There's no way anyone could ever consider Space Mountain or Everest overrated. Both of them are great rides and one of those coaster's finale is working at least.