Critics loving it and people going back to see it again definitely suggests more people think it's a quality film than don't.
Who gives a flying **** what "mainstream critics" say? Most of these pretentious twats aren't into Star Wars at all, and it is in their benefit to give a good score so that Di$ney gives their organisation freebies like early screenings. The only reason it's being "critically acclaimed" is because it has a Star Wars tag on it. Take a look at
Cinemascope for Episode 1, they gave it an A- average. No friggin' way it's that high, same for this movie. The audience reviews are what counts, and
plenty of them are quite eloquent in pointing out the various flaws, even from people who had low expectations in the first place or aren't necessarily Star Wars fans.
You have no way of knowing how many of those are going back to see it twice/thrice/etc. Considering the relative drop compared to the other films, it is safe to say that a lot of them aren't going for multiple servings. Then there's the fact that people coming back from Christmas/people waiting until now because of the crowd/etc.
If this is a "quality" film then so's Transformers. Some people are saying "oh see it a 2nd time, you'll like it then"... if I have to see it a 2nd time to like it, then it's shit from the beginning. The horrific writing, plot, lack of character development will still be there, possibly magnified.