The story is mainly about Kelvin Kirk learning to be less of the cocky dipshit he still is at the end of '09. He’s still riding high from his victory over the future Romulans, so he really doesn’t respect the seriousness the Chair should command. You see this in the completely unforced error at the start of the film–Spock is (for some reason) dead to rights, and Kirk decides that the power of friendship is more important than the Prime Directive. Pike rightly reams him out for this, but the character thread really comes to a head when the USS Vengeance catches up to Enterprise and prepares to utterly destroy her. Much as I complain about the movie, I do like this little moment of helplessness from Chris Pine’s Kirk. Staring down the larger ship’s guns, Kirk can only watch helplessly and apologize for leading his crew to their deaths. It has the same vibes as Kirk from Generations–he didn’t believe he was dying until he actually did. Obviously, the general thread of Kirk actually taking responsibility for his crew culminates in him doing percussive maintenance inside of the Warp Core and dying for Enterprise’s sins. He gets better, but honestly I can accept this as the transition between cadet Kirk of the 09 and the actually quite competent Captain Kirk in Beyond.
Spock is the other big character in this movie. Sad as it is, this is the only real time we get to see Kelvin Kirk and Kelvin Spock’s friendship explored in depth. They were at each other’s throats for most of '09 and Beyond focused more on McCoy + Spock’s relationship. Spock’s friendship with Kirk is the main avenue through which they explore Spock’s classic dilemma of his Human vs. Vulcan sides. As cynical as I am about them recreating the end of WoK in reverse here, I will at least concede that Pine and Quinto did well with what they were given.
Main complaint, besides Cumberbatch being Khan: they totally wasted Bruce Greenwood’s Admiral Pike here. I’m of the opinion that Kelvin Pike was the best version we’d seen prior to Discovery, and probably did more than a little bit in reviving interest in the character. Here he gets stuffed in the fridge like half an hour in to make Kirk mad/sad. What a shame.