This movie was so different than its predecessor, that some didn't believe it was a "true sequel." But it is, and there is a grand change in action. It moves from fighting some aliens on a deserted planet, to resisting the strongest force in the galaxy.
You'll see some cool new planets, new technology, and new people that fit into the "Riddick Universe" that is being established through movies, anime, and video games.
Riddick = Badass.
This movie = One of my favorites.
You should watch it, if you haven't already.