I loved it. Liked the last one, but thought this was a substantial improvement. I'm not sure how I'd rate it versus the original Khan movie. Honestly, at this point, comparing them feels too much like apples and oranges to me.
I liked that the whole movie wasn't Kirk against Khan. The simplistic and frankly boring nature of Nero was my biggest problem with the last movie. Peter Weller and Cumberbatch both did a fantastic job and the roles were written well. I thought the Kronos section of the movie was the best part and I hope we see more of the Klingons in the next movie.
If I have to complain about something, and it's the internet so I think that's a given, I will single out the uniforms of the Vengeance crew as being atypically ugly for a movie with such a beautiful production design. A minor gripe to be sure but I thought they were genuinely unattractive. The Klingon ships weren't exactly memorable looking and the only place where I clearly prefer the older designs, but I liked them okay.
I'll be going again this weekend, more than likely. For the record, I chose to see the movie in 2D.