In my first review of Star Trek ("Star Trek is DOA"), I blasted it's lack of realism. I went to see it again and, I have to admit, I liked it much better.
I think if you go into this movie expecting it to be a bit far-fetched--something along the lines of the first Starship Troopers--you'll like it a lot better than if you expect a 100% plausible story line (I'm not being sarcastic, I actually liked Starship Troopers). My expectations, after being disappointed by the first go round, were right around zero. I was surprised that I was actually enjoying my second viewing.
I still had trouble swallowing some scenes, e.g., Kirk's Spiderman jump, near the end, in the Romulan Mining ship. I initially said 50 feet--it might be even more! Scotty's Willy Wonka tube ride, and his munchkin-alien side kick, were still painful to watch. Also, there were no marks on Kirk's face after Spock pummels him or after Nero pummels him--kinda strange (Kirk was bloodied in the bar fight). He's hit so often in the movie...maybe he developed an immunity to injury??
The Sulu/Kirk mining platform sequence is probably my favorite scene.
I think all the actors did a fine job, they were fun to watch.
In my final analysis, I'd say Star Trek is a fun and flashy movie, with a handful of gritty, realistic scenes. I would have preferred a little more grit and little less giggle, but it is what it is.