I can understand that. While Yoda and Sidious with lightsabers doesn't really bother me, I think it was cool to have Jedi/Sith that didn't use tangible weapons to fight. There was no denying the pure evil power of Palpatine in ROTJ when he unleashed his force lightning on Luke. I think most people assumed that Yoda was the Jedi equivilant of him, and would use purely the Force to fight with. Giving them lightsabers, although wickedly cool looking (at least to some), diminishes their power in a way. The lightsabers bring them down to the same level as all the other Jedi and Sith.
Again, it really doesn't bother me at all, but I can completely understand why it's a let down for a lot of people.
I enjoyed the first two prequels, and I'm sure I'll enjoy this one too. It's a completely different level of enjoyment from films like Amelie or Down By Law (my two favorite films), but it's enjoyment nonetheless. It's comparable to, say, eating a really tasty candy bar VS. a perfectly grilled fillet of salmon.