I saw the movie for the first time on Wednesday December 16 (that's right, two days before the US premiere, for some reason a bunch of western European countries got it early), at 10 am, in 3D. It wasn't even sold out, maybe 1/3 of the seats occupied, but then, I imagine most die-hard fans who bothered to take the time off work that morning would be going to the IMAX version.
Saw it a second time the next day, Thursday 17, also 3D, at 3 pm, and there were maybe 30 people in the audience. I have to say, at that point in time I started to feel a bit worried about the popularity of the movie.
Thankfully, the next Sunday I saw it in the UK in 2D, and the theater was about 90% full, and last week (i.e. during the holidays) in the IMAX it really was sold out, so I guess a lot of people did indeed wait until the holidays to go see it.
I'm going to see it for a fifth time

tomorrow, again in 2D. I must say, all three version have their advantages and disadvantages. For some reason, I thought some of the details were clearest in 2D, and I didn't really feel like the IMAX added much to the movie, because the movie just wasn't made for it.
And yes, I'm a die-hard Star Wars fan. Been a happy addict since 1994 or so, when I discovered the original trilogy, and soon afterwards, the Expanded Universe novels, and dare say I read all the books set after A New Hope. Didn't bother with the whole prequels novels era, mainly because I'm a Luke fan.
As for my thoughts on the movie: (text in white, I cannot seem to find a spoiler tag)
Really wish we knew more about Rey, about her backstory. One day I think she is Luke's daughter, the next day I'm leaning towards Rey Random (either a ex-student of his "academy" or else really just random person in whom the Force awakens, although it's clear that she's been developing her survival skills for years on Jakku.
And of course, being such a Luke fan, sure, I wish there was more of him in the movie. He had better have a BIG and important role in VIII, and not be killed off right away, because seriously, that would have defeated the whole purpose of VII. They go out of their way to make the viewer understand he is needed, if they then proceed to kill him off so they can give Rey the spotlight, I will be seriously bummed, no matter how much I like Rey.