I saw the film when it opened in the states on Thursday, and I have to admit, it's pretty much what I was expecting. I'm not going to spoil anything here, but I definitely think it could have been better, although it did have its high points. Unfortunately, it came off as a bit rushed to me, and I honestly felt that there were too many missed opportunities in the film overall.
On the positive side, I will say that Karl Urban and Simon Pegg were superb, and that there definitely wasn't any problem with the actors; the problems, at least in my opinon, were clearly issues with writing and overall execution on the production end of the film.
One thing I will praise on the production end though is the new "warp drive" effect. I've made it abundantly clear that I hated the "warp drive" effect in Trek XI, so it's nice to see STID returning to a more traditional "rubber–band" style visual effect for warp drive. I don't really think that counts as a spoiler, but if it does, I'm sorry for not tagging it as such.
Oh and I have to admit that I'm curious to see what this film will bring in at the U.S. box office; the IMAX 3D showing I was pretty empty, (I think there were more people in the opening day showing of NEM that I was at,) but then again, it was a 1:00P.M. showing on a Thursday afternoon, so it could just have been an issue of timing. If this is a pattern though, I'd consider it a cause for concern.