I'd call this film 'fun.' It has a few deep subjects, but they almost seemed glossed over or not explored as deeply as one might wish. Instead we have a very kinetic, fun, action driven film that till pays a lot of homage to the original.

What works: The script has the crew splitting up after the first act, giving each set a chance to shine and build their characters a little. Chris Pine always seemed a bit too young and green in the earlier films (a fact those films actually took advantage of), but here he seems to actually have grown into the role. He's having a bit of a pre-midlife crisis that actually gives him a bit of an emotional arc that works well here. Spock/McCoy especially benefits from this set-up, as they really seem to nail the relationship between these two from the older material. Simon Pegg co-wrote the screenplay, so Scotty has a bit to do in this one - but he never tries to take over or steal the movie. He is more of a set-up guy for the other characters, but still manages to shine in his own right. Sulu and Uhura are a little underutilized, but still manage to have their moments. To say more would be spoiler-y. Finally, Chekov is given some nice screentime - appropriate considering the tragic death of the actor. There is a moment after the first credit sequence in memoryof him and Nemoy, and they cut off the soundtrack allowing a moment of silence. The fact the movie's soundtrack was rather bombastic and loud at times means this moment stands out even more, and was a nice touch. The special effects were, at times, breath taking...

What doesn't work.
... except when they weren't. Me and Eddiebear noticed a few green=screen shots where the CGI looked rushed, fakey, or not well matched. Still, considering the heavy fx nature of the movie means a few will sometimes slip by, but they are noticeable enough to pull you out of the moment a few times.
The editing uses a lot of superfastjumpcutstomakeintenseactionsseemmoreintenseandwowlookcanIeditandwedon'twantviewerstogetbored.... yeah, slow the fuck down so we can actually, I don't know, ENJOY some of what is going on. The movie seems to be trying to sell us on how intense the action is when, in reality, it's not needed - which makes it even MORE annoying and unnecessary. I blame a bit of this on this director.

The villain seems a bit weak and by-the-numbers at first, but the final act fleshes out him and his motivations. Sadly, it's too little too late, and had they given us a few nuggets of this info maybe half way through the movie, the final motivations would be more coherent. He's not a bad villain, but the first rule of building a mystery is to clue the audience in on the fact that there IS a mystery. Otherwise it just comes off as an information dump shoe-horned in before the credits roll.

So yeah, it's probably worth going to see in theaters, especially if you like Trek and want a fun experience. I'd give it a solid "B".