I heard it was good if you like Doom games (which I do, weeee!!).
The reason The Rock isn't focused on is because he's sarge, who's not the main character. Karl Urban plays the lone marine (main character in doom games) I think, so I've read. Yeah, anyways.
Also read in a review that towards the end it goes into an FPS viewpoint or something, which has to be kinda neat for a movie. Definintely gotta see this. Probably will wait for it to come to blockbuster or something....I hate movie lines and theaters and stuff.