Definitely the most fun I've had at the movies in a long time. Though perhaps that isn't saying much since the last time I actually went to the movies (as opposed to having the movies come to me, so to speak) was when I saw Madagascar 2 with my sister, her husband and our children. The movie was pretty funny (the penguins! God, the penguins!), but what I liked best about it was watching the kids enjoy it. Star Trek, on the other hand, was enjoyable all on its own. More than enjoyable. It was pretty damn awesome. With some caveats.
The cast was fantastic. I'm not going to bore you with stuff you either already know or can read elsewhere or will soon find out, but my favourite sequence is when McCoy (and I was going to write that as 'McKoy'--I'm such a SGA fangurl) uses liberal and dubiously Hippocratic applications of hyposprays to scam Kirk onto the Enterprise. I also enjoyed how often Kirk almost fell off something. Or got strangled. Or got hit in the face. The guy is nothing if not consistent in his pain.
Chekov was adorable and wonderfully competent, and Sulu kicked ass. Almost literally. When he told Kirk that his combat expertise was fencing I was remembering TOS ep The Naked Time, when Sulu is kind of prancing around with a foil. I should have remembered that fencing training also includes sabers. And back flips, apparently.
The whole cast was fantastic, though Karl Urban really stood out for me as McCoy.
What I didn't like was right at the beginning. Though it was brilliant the way this Trek instantly became an Alternate Universe (a trope beloved of fanfiction writers everywhere) and thus freed up the canon to do whatever the hell they want, the fact that Kirk's daddy dies pretty horribly (though heroically, of course) scant seconds after his wee bairn is born broke my heart. As a parent, I just couldn't shake the horror of that: a father missing his son's life, and a child never having a father. For me it was even worse than Spock losing both his mother and Vulcan, though his reaction to both was portrayed beautifully.
I also didn't like that unlike all the males in the cast, Uhura gets almost nothing to do but comfort Spock. Sure, she's presented as a brilliant linguist, top in her class, can speak all three dialects of Romulan fluently, etc. etc. But while Sulu gets to do back flips and save Kirk's life; wee Chekov gets to be adorable and save Kirk and Sulu's life with his wee adorable genius; Scotty gets to save Kirk and Spock and Captain Pike's life and then the whole ship by ejecting the warp core (and really, it wouldn't be a Trek movie if they didn't do that); McCoy gets to be sardonic and hilarious and competent; and Kirk and Spock get to do pretty much everything else including saving Earth...Uhura gets to speak Romulan and be coy about her first name. Every single last one of the bad guys are guys, too, though that's just par for the course in sci-fi. God forbid a female Romulan miner might lose her beloved husband and then go on an epoch-spanning rampage of vengeance. Or, you know, have lines.
What the movie did do pretty well (aside from the main plot and characters I mean--I really did enjoy it) was have characters of colour throughout, though Uhura was the only one in a major role. At least they were obviously part of Starfleet and did cool stuff too. I just wish they had more women. Maybe Uhura can do something pivotal in the next movie.
TL;DR: Great fun. I'm definitely going to watch it again. Apparently the leads have signed on for at least one more film, which makes me very happy.