It was decent, entertaining and coherent, and it did justice to the Star Trek franchise.
However, I have a few things to nit-pick. Firstly, James T. Kirk was fucking annoying and obnoxious. I know he's supposed to be "daring" and everything, but I would have expected him to be a bit more responsible and well-mannered. Secondly, I don't think that Sylar should have played Spock. He made Spock too emo and I just don't like that guy's face anyway. I know it was a key part of the plot that Spock is only half-Vulcan and therefore cannot control his emotions like other Vulcans can, but I think Sylar made him a little TOO emo, almost like Anakin Skywalker. Still, he wasn't as bad as Kirk, and there were many Spock moments that I liked.
Another thing I didn't like was how the movie tried to ride on the familiarity and nostalgia of the original Star Trek crew. Having all those characters shoved in my face felt a bit awkward, and the "quirky coincidences" of how they all met didn't seem very natural or relevant to the plot that all. I know it's good to be loyal to the original show and all, but it seemed they were there just to whore out the movie to the Trekkies. Like they give each character a little screen time so they can say "OH LOOK, WE DIDN'T FORGET HIM!"
Leonard Nimoy, on the hand, was brilliant. I was a little skeptical at first when he appeared, thinking "Is this going to be another one of those pretentious Star Trek moments?" But no, he was very smooth and natural as the old Spock, and he filled the role perfectly, just like he used to. And it didn't seem artificial or unnecessary either, I think his appearance was well-attached to the plot.
Despite my complaints, it actually was a pretty good movie.