Well, I won't reveal spoilers as it's too early to publicly discuss but the film opens really strongly. You're thrust into things not knowing who characters are, what's going on, when things are, etc and this works incredibly well to guide us into the journey of Kirk from rebel to captain. You need no knowledge of Trek at all (though there's a few nods to fans in the details) and the whole thing is given a nice lick of polish (though those of you who thought the bridge of the Enterprise looked like a mobile phone shop will at least know what brand they sell after this!). The effects are great, there are no slow bits at all and the action pretty much carries on throughout the entire movie.
There are surprises: a larger role for Uhura than expected, a surprisingly good Scottish accent by Simon Pegg (though his wife is of the Scottish persuasion so he should have plenty of practice!) and a more pivotal role for Leonard Nimoy than expected. The new Kirk is pretty good actually...never quite reaches Shatner's easy charm but ably fills his boots otherwise. Quinto is great as Spock, at no point making me think of Sylar (so that's a feat in itself!) and Uhura is likable for the first time (she always seemed so confused on the TV show and undeservedly up herself in the movies).
There are a few niggles: Karl Urban pulled off a great DeForest Kelly approximation as Bones but still came across as kind of bland and the weird facial skin of Kirk and Spock's five O'clock shadow become weirdly distracting. Similarly, the perennially youthful Winona Rider seemed suddenly aged and the internal debate about whether they aged her to be believable as Spock's mum or if that's her natural look threw me out of the film in places (though that may say more about the random thoughts that distract me in films!). The plot doesn't really kick in until midway in a really fast-spoken info dump and I was like "Was that the plot they were just explaining there?". The second half of the film kind of steam rolls on to a satisfying but not great finale. There were a few jokes but nobody laughed at them.
So, overall? Great fast-paced reinvention but lacking the deeper plots and characterisation of the earlier films...