Maybe the movie will be one on it's own that will set the base for the Disney run, I don't expect a true OT feeling since the OT was a product of it's time but at least I expect an attempt to pay respects to the OT. Also the script writers and the director are better than Lucas so at least it will be a more consistent film.
Worst case scenario: TFA will easily fall right above the PT, kinda sucky but entertaining .
Best case scenario: It will be better than RTOJ like Silverwook said.