This is NOT the Star Trek you're used to...

Rating: 10/10 (19 May 2013)

...but this movie is definitely worth watching, if you can allow yourself to enjoy new actors playing old roles. If you can't accept the fact that all of the familiar faces are replaced, don't spend the money to watch it - you won't be able to enjoy yourself.
That being said, I just got back from the theater and I thoroughly enjoyed myself. As a lifelong Trekkie and a big fan of Benedict Cumberbatch, I made it a point to go see it on the opening weekend.
I'm not going to try to spoil the plot, but existing Trekkies will be pleased to see throwbacks to the older movies (**Spoiler: To the second film in particular**).
Everyone's acting was top-notch. Spock (Quinto) and John Harrison (Cumberbatch) were both exceptionally written. I would definitely watch this movie again. And again. And again.