I enjoyed it. I have no issue if they want to explain away some of the many plot holes in the last movie as long as the story holds my attention, and this one did. My principal issue is that making the movie the Wrath of Khan stole a lot of its emotional resonance - Kirk hadn't really wronged Khan, his relationship with Spock is in its infancy, and the reset button doesn't allow the audience any time to grieve.
If they want to round out Khan and bring him back for a proper showdown sequel in the comics I have no issue with that. I'd still like to see him in charge of a multi-racial (Klingons, Orions etc) terrorist group.