Saw it at IMAX. Was good, really enjoyed it. When I left the house the internet said there was 50 some tickets left, when we got there it said sold out. As observed above the place was packed out when we were leaving. This aspect of it is usually meaningless to me but its "fun" for a few of the more nerd-centric films.
IMAX really is the way to see effects / scenery heavy movies. The large size and wrap-around "arc" of the screen really add a lot to the experience. (Similar to the oldschool Cinemascope film tech) Almost like a 3D effect without the glasses. Some might say better than 3D effect as it gives a "in the movie" feel. Don't sit in the back, get there early and sit somewhere in the center/front. The effect is lost quite a bit (maybe even totally) if you sit on the sides or in the back. I'm still trying to figure a way to get some money I don't have (one of the two key reasons I didn't go to Oblivion this weekend), to go see how they work this at the IMAX Dome at the DSC. (I currently wouldn't suggest going there as I'm skeptical of how a traditionally filmed IMAX movie is going to work on an IMAX[R] screen. Seems like it would look pretty odd. IMAX[R] is probably the ultimate way to see a movie currently, but feature films are not filmed for this format, only special documentaries and such get the proper treatment as far as I'm aware.
They did an interesting thing to escape the wrath of us ST lovers with the time travel aspect of it. J. J. Abrams has long stated that he wasn't a star trek fan to begin with, and thus the ST faithful were skeptical of this interloper for a long time. The folk that look down their noses at us ST enthusiasts won't care either way, but too bad, deal. Regardless, he delivered the goods. The "current" time of the star trek series will have to be set as this movie. With huge changes to the star trek story, two of them being the lack of the planets Vulcan and Romulus(home of the Vulcans and Romulans, bizzare how that works huh?) Which are major staples of the Star Trek storyline and have been for 40 years. Now in the new time line they both are destroyed, with both vulcans and romulans being endangered species. Won't have to worry too much about them evil romulans anymore I wouldn't think. No appearance from either of the two most liked "bad" races (Klingons and Borg) was interesting.
This alternate timeline allows a loophole for a few of the major changes to the backstory they threw in in the movie to slide by as they can be considered part of the oft-mentioned (but never explained) "Temporal Distortion", in this case a huge one. Ok /geekmode off.
Easy to watch for most everyone as noted by the reviews. Its in line with Star Trek IV: The Voyage Home ("The one with the Whales") in that aspect. Both pretty much universally liked.