I'm assuming this thread is not requiring spoiler tags. Be warned that they are in this post however.
I went to the midnight early (first) showing. There were about 30 people in the theater. I was the third one there. I was very surprised to see that I was clearly the oldest, at 50, to be there. The entire audience was clearly under 30. I guess Paramount is getting their new audience.
That being said, my reaction contrasted very differently to the rest of the audience. My group reacted positively to 'Khan' whereas I groaned inside. I really wanted a new bad guy. Especially after being assured that it would not be Klan by TPTB. When Kirk was dying, one member audibly muttered a confused 'WTF'? I don't think it was a 'why rehash this scene with Kirk? "wtf", but more of a 'Holy crap.' And 'How are they gonna fix this' "wtf"
Overall the audience responded very well to the movie with applause at the end. I did enjoy the movie. I thought it was well done. I'm still struggling with the 20 year discrepancy of Khans appearance and the parallel/alternate occurrences and reactions to what occurred in the original timeline. I think if you can separate what 'we' know has happened and view it through fresh eyes, this is a very good movie. I'm going again this afternoon. btw.
The theater I saw it in was about 3/4 full at 7:30 (IMAX 3D). There were quite a few of us AARP-types, 30-somethings, and my daughters were relieved to see a smattering of tweens and teens.
The only audible sound I heard when Harrison revealed his true identity was an, "OOOh," from a woman a few rows ahead of me. And it was an, "oooh" as in, this is going to get interesting.
My wife (an unspoiled non-Trek fan) truly said a confused, "Wow," as in "they really did that?" when Kirk died, and looked at me like, "Kirk's your man, why aren't you sobbing?" (Of course, it's because I was spoiled rotten.)
As far as having fresh eyes goes, to paraphrase Kirk in TUC, if there's going to be a brave new world, our generation (of fans) is going to have the toughest time living in it. Fans can be very frightened by change.