First off, this is not Star Trek as you've known it, they really have gone and pressed the big red reset button in a very dramatic fashion yet that in and of itself is not necessarily a bad thing, to paraphrase Scotty, I like it. It's exciting. While the story seems very contrived in parts like for example Kirk just happening to be booted out onto the same planet that Spock is on not 10km down the road from Scotty, it holds together well enough that such matters for the large part can be ignored. In fact the villain, Nero, and his plan to wipe out the Federation one planet at a time is all very silly but that's not really what the film was about, it merely provided a back-drop to the formation of the crew which, I felt, the film dealt with admirably.
The film itself certainly was gripping from the get go. The opening battle between the Kelvin and the Narotu, or whatever is was called, certainly was epic, definitely attention grabbing and a great way to start the film. It meandered a wee bit in the middle, such as the daft creature chase which served no purpose (It actually reminded me of Phantom Menace, there's always a bigger fish, I was waiting for a third creature to appear), but nothing too distracting. Most of it was fun to watch and the film certainly delivered the massive scope that a Star Trek film deserves, not just with impressive visual effects but with random aliens thrown in for good measure, something which the latter Star Trek films seem to have given up (Insurrection, for example, with it's stretchy faced villains

).
Of course the standard thing to comment about any sci-fi film is the quality of it's special effects and in this case they really were special but with ILM behind the scenes is that really surprising. The one thing that annoyed me was that stupid lens flare all over the place, once or twice would have been grand but it was in every ******* scene serving only to block the action. Maybe they though it gave the film a more realistic appearance, to me it just looked like bad cameramanship.
The Enterprise itself was stunning and certainly seemed larger than life with the engineering section looking like an engineering section. However, they seemed to forget this very functional look the design department appeared to by trying for when it came to the bridge, everything was ridiculously glossy and blurry, a form over function approach which didn't gel well with the rest of the ship.
There were a few things that bugged me however;
The script writers appeared to not give a toss about the fact that there was a Star Trek before their film came along and blithely set forth to do as much as possible to set their vision of the Star Trek universe apart yet every so often they'd throw in a random quip in an obvious attempt to appease fans. It just felt like they were ticking boxes, ie Chekov mispronouncing Vs, check, Sulu with a sword, check etc.
The music, it was crap. I used to like Michael Giacchino's music back when he was keeping it very minimalistic during the first season of Lost but nothing since has really struck a chord with me (well, okay I liked that bit during the credits of Cloverfield, can't think of the track name). Worse than that though, there was so much potential for the score to have been much more than it was, why didn't they include an updated version of the original theme, in my opinion it would have worked very well with the style of music used throughout the film. Instead the original theme was thrown in at the end in a very jarring, box ticking manner with Spock Prime, as he is now known, doing the final frontier voice over.
Phasers. This perhaps bugged me the most. Phasers fire beams of energy, not pulses. How difficult is it to get right
Edit: Oh and red matter, could they not have come up with a better name... Oh look, we have this stuff of which a single drop can create quantum singularities and it's red. What will we call it?
....
Big shiney red orb of doom?