My take on this is very different than yours. I hated ROTS with a passion. Don't think I was even able to finish it the first time I watched it (I went back and watched it later, because people kept referring to things in it I hadn't seen). I think it's the worst of the prequels by far, and possibly one of the worst movies of all time.
Episodes I and II were OK. I like to get on the bandwagon and bash them for the fun of it, but really, they are watchable, and I've gone back and watched them a number of times. Interesting minor characters, good action scenes (especially the multi-layered battle at the end of Episode I, similar to the threeway final battle in ROTJ, but also the other action scenes, in both movies). The detective type story in Episode II was an interesting direction, too. Overall watchable, decent films.
But I think the biggest problem with the prequels was that most people (myself included), expected George Lucas to deliver the exact same thing as the OT, and George Lucas didn't deliver that (he wasn't trying to, as far as I can tell).
As for Episode 7, I don't doubt it will suck. I just don't think it's realistic to hope that J.J. Abrams, with his trite saccharine superficial style, and even more so as part of the Disney commercial machine, can possibly deliver a solid Star Wars film. But I'm pretty sure I'm going to enjoy enough of the elements of it to make it worth seeing (Han Solo, Chewbacca, the Millenium Falcon, John Williams' music, the lightsaber duels, the aerial dogfights, and just the overall feeling of returning to the Star Wars 'world' again).
I'm keeping my expectations low, but I am looking forward to seeing it in a way. I'm being realistic that it will suck, but I'm hoping it won't suck too badly.
Anyway, that's my take on it. Hope you don't mind the long comment. :)