I completely and totally enjoyed it! It was an absolute blast!
It had a solid plot that (for the most part) made sense and worked. There was some great action that worked well with the characters and wasn't too chaotic. The characters themselves felt like the "old" Star Trek characters, but with some new twists and growth that should work well in the future.
The movie itself fairly neatly sidestepped the continuity issues that could have dogged it in the future. Essentially, this is a "reboot" of the Star Trek franchise from a solid base (graduation from Starfleet) with some small (and some big) changes that clearly show that this "new" Star Trek is not going to be bound by past Star Trek history but is still going to be, in many ways, the Star Trek that people know and love.
Overall, I was very pleased by the movie. In the "Trek or Wars?" question I've always been more of a Trek person but also have felt it grind down under its own weight in the last few incarnations. This is a fresh start for Star Trek one that I believe will lead to more popularity, more movies, and maybe even a TV series in the next few years.
I had a few nits to pick, which I'll cover in the spoiler review (coming later). But overall STAR TREK is highly recommended, for Trek fans and non-fans alike.