So the young Kirk is a wise guy. Of course he is. He's still a wise guy today, doing commercials for "Priceline" - but wait, that's William Shatner, not Kirk. It all gets mixed together in the mind. As Kirk, Chris Pine doesn't imitate Shatner, but he evokes his confidence and breezy, jolly narcissism. At 10 years old, the young Kirk is taking the family car out for a joy ride, and as a young man, he's getting into bar fights. He has brains and nerve to spare, but he's going nowhere on Earth. Space is the answer.
Also this bit about Leonard is priceless:
Leonard Nimoy shows up as the old Spock, and he's not just there for a perfunctory blessing. He serves both a story function and an emotional function. At 78 (and looking not a day older than 79), Nimoy, just standing there, is a reminder of the passage of time and the glory of it all. He gives this new series a kickoff that it just might deserve.
This review is pretty much spoiler-safe, but if you're like JK and don't want to know ANYTHING about the movie, don't read it.