Well I don't know if I've earned "Niner" status since I haven't seen the whole series yet (just started Season 7), but I seem to post in here more than other sections and I recognize more people in this thread (and therefore feel more comfortable in it) than in the official discussion thread, so I decided to post my thoughts here.
The beginning
For about the first hour of the movie, I was in heaven. I can't believe how moving and poignant the pre-credits sequence was. I guess it was a pretty obvious and unoriginal way to set up the character's backstory, but softie that I am, it totally got me. This is the first movie where I felt like crying before the opening credits even started! Weird how the most touching part of the movie could come so early!
Nero
I spent the first hour anxiously waiting to find out Nero's motivation was. I thought all the movie needed was a plausible backstory for him and everything would be set up perfectly. Unfortunately, I think the moment his history was revealed was when the movie first faltered majorly. All the exposition to explain Nero's hatred of Spock and how he and Spock travelled back in time was so contrived, it reminded me of Nemesis (not just because the guy was a miner)...it just smacked of really forcing someone into a villainous role by implausible backstory machinations (i.e. Shinzon), rather than having him seem naturally thrust into it (i.e. Khan).
Continuity/SFX
To be fair, the writers had a tough task trying to tie this together with the original series and allow themselves the freedom to break continuity at the same time, but I think they could have done that with a little more finesse. Thankfully, the contrivances of the plot were pretty much the only thing that bothered me. Some special effects were a little too murky and busy for someone with an "old school" sensibility like me who prefers battles on a smaller scale so it's easier to keep track of where everyone is and who is hitting who (I hate when there are too many ships fighting like in Star Wars, or in this case, when the ships are so out of scale with each other that it's hard to tell where each is during combat), but that's no big deal. What exactly are these "lens flares" so many people are complaining about?
Kirk, Spock, & McCoy
For me the movie succeeded despite a painfully convoluted, plot hole-riddled story because the characters and actors saved it. I found it excellently cast across the board. All the characterizations were spot-on (especially McCoy) and watching Pine naturally blossom into the role of Kirk as the movie went on was wonderful. His performance is an impressive balancing act, bringing some of the best qualities to the role that Shatner did (the warmth and playfulness, particularly in his first encounter with Uhura) while discarding some of the more distracting ones so he doesn't seem to be simply aping Shatner (i.e. the stilted dialogue) as he brings a fresh take to the character. It was almost eerie how much he sounded
exactly like Shatner when he cheerfully said
"Bones!" at the end, but I loved it. I thought Quinto and Urban were immediately convincing in their roles too. Urban might have been trying a little too hard to capture Kelley's mannerisms at some points, but I found it endearing.
Chekov, Sulu, and Scotty
Chekov's accent was really distracting. Until Spock's mother bit the big one, the audience I was with laughed at
every single thing he said, even when it wasn't supposed to be funny. I saw it with a non English-speaking crowd and even they could tell how goofy his English accent was, but I think we need to cut the guy some slack. The actor was sort of stuck having to be a little cartoonish by design. Maybe we stopped noticing because we're used to it by now, but even in the original series, that accent was really over-the-top and more a stereotype of how Russians sound than a convincing accent. I believe he did the best with what he was given. He looks nothing like Chekov, but made an admirable attempt at affectionate mimicry.
It was nice seeing Chekov's specific skills highlighted a little more, and Sulu's love for fencing allowing him to kick ass in a sword fight was a cool touch. I wish he got more moments like that. Pegg's Scottish accent was way thicker than the original (probably easier for him than Doohan's since he's British), but otherwise, I thought he was perfect too, if a little underutilized. At the end when he was yelling about "giving her all she's got", I felt a warm tinge of nostalgia as it really felt like we'd come full circle in the Star Trek franchise, even though it was a shamelessly obvious reference.
Homages
I'm a little conflicted about the homages (especially some of McCoy's lines at Spock)...it's cute to have these references, but I kinda wish they'd say something
new, rather than just using old lines from old shows and movies. There was a little too much
Wrath of Khan fanwanking with the parasite and Spock's "friend" line (I think it kind of cheapened the original, although it was sweet), but I was actually wishing they referenced it a little more at one point. When Nero yells,
"SPOCK!" twice, they missed a prime opportunity to have the second yell accompany an establishing shot.

It was cool to see Nimoy again, but a huge bummer that his first order of business was to explain the dumb exposition through his mindmeld. Good thing they gave him some uplifting conversations with young Kirk and Spock too.
In conclusion...
It's always frustrating to have to watch great characters and great performances stuck in a mediocre story. The first hour 'getting to know you' period was magical, but once the actual conflict and the villain's history were revealed, the movie kind of went off the rails, only to be redeemed somewhat towards the end as the crew comes together nicely. I think the movie was just what the franchise needed and a lovely moviegoing experience. I was smiling, laughing, and being entertained about 85% of the time (when the ludicrous plotholes and exposition weren't annoying me) so despite its flaws, I'm glad I saw it. I just hope next time we get a better conceived story. These actors and characters deserve one.