I didn't hate the movie; in fact, I had fun with the first half. I still like this cast a lot, and some of the energy from the 2009 film was still there.
But I had some big, big problems with the second half. First of all, I really wish they hadn't gone down the Khan route at all. Khan has already been done brilliantly; plenty of other concepts from throughout the franchise that maybe didn't work as well. Why not choose one of them and do it right? Or better yet, why not do something completely new (which was the whole point of rebooting, I thought)? However, if you're going to do Khan, why not really delve into why he was so evil, instead of just having "Spock Prime" show up and remind us how good That Other Movie was?
And speaking of that, I never thought I'd say this, but I thought there were actually too many references to the older films and series. There were times when I felt like I was watching an actual remake of Wrath of Khan, and it became distracting. The movie really imploded for me during the "death" scene, which failed on so many levels. The awkward inversion of the original WOK scene coupled with the fact that we knew there was no way they were actually going to leave Kirk dead sucked all the drama out of it. Then Spock suddenly Shatners out "KHAAAAAAAAN!!!" and I almost burst out laughing. One of the most ill-advised and inappropriate "homages" I've ever seen in a movie. Ever.
Then, the device they used to revive Kirk was also ridiculous. I know it was established way back in "Space Seed" that Khan's blood showed remarkable regenerative properties. And of course, it was used at the beginning of Into Darkness to heal a sick little girl. But it's quite a leap from both that and reanimating a tribble to bringing a dead, irradiated adult back to life, and a clumsily set up leap at that:
"Bones, what are you doing with that tribble?"
"It's called plant and payoff, Jim."
I just didn't buy that at all. And incidentally, Starfleet now has access to a serum that can cure death.
And I guess I appreciate the attempt at social relevance with the terrorism theme, but it felt rather perfunctory, with mostly just lip service given out a few times.
It's really too bad; there are some things in the movie I enjoyed, but it just fell so completely apart in the third act that no amount of witty banter or flashy effects could save it.