First of all, I am a die-hard Trekkie. I have seen all the movies many times (even the ones that suck), and I even watched 'Enterprise' out of some misguided sense of obligation. Having said all that, I LOVED this movie. I have NO problem that they went with an alternate time line theory. In fact, I think it was a very clever way to both honor what had come before, and to start something new.
To all the people who are saying "Oh my God! What have they done? How dare they tinker with our beloved Star Trek time line and canon!" I have this to say. While you are certainly entitled to your opinion, if your emotional well-being is tied to a TV/movie franchise, then it's time to rearrange your priorities.
Why is it so impossible for some people to simultaneously love what came before, and embrace something new? It's just unbelievable how some people just want to conjure up the same tired old retreads that bogged down the movies and the TV shows after a while. What were they supposed to do, somehow resurrect Khan for another go around? Throw Sisko and Janeway on the same ship, just to see what happens? I thought this movie had the perfect respect for all of the elements that made us love Trek in the first place, while refreshing it for a new generation.
One last thing, let's not forget that when Star Trek premiered 40+ years ago, the ratings sucked, no one liked it, and it lasted only three seasons. If it were not for a die hard fan base to keep it going, it would have ended in 1969 and that would have been it.