Though this is sacrilege, one can credibly argue that A New Hope is pretty boring until after the Mos Eisley take off, especially after watching Revenge of the Sith. It's not really until the end of The Empire Strikes Back that the whole saga begins to really come together.
No, among my biggest beefs with the prequels was that none of the Sith apprentices had any character development, and really served no purpose other than cool bad guy. I mean, Darth Maul had an awesome fighting style, but that's it. Darth Tyranus really wasn't in the films save the end of Attack of the Clones and beginning of Revenge of the Sith. Unless you watched the animated Clone Wars series or comics, General Grevious came out of nowhere.
Visually, the prequels have a lot more going for them, but you know, the originals were only made in the 70s and 80s so go figure.
ROTJ is fine as a film, the Ewoks are a little hokey, but it didn't kill the movie for me. I mean, the Jawas aren't really that much different, you just don't know what they look like.
The special editions only really screwed up one thing IMHO, and that's Han not firing first.