Riddick is a good character, not because he's particularly complex, but because he has an archetypal anti-hero quality to him that makes him appealing. In this third installment in his story, we get to see more depth to him, which is interesting because he doesn't have that many lines.
Now don't misunderstand me, Riddick is the star and he's in most of the scenes. It's just that in the first third of the movie he is alone for the most part, and to be honest, it was the best part of the film. Watching Riddick do what basically amounts to an alien world survival documentary was more engaging than the action in the final act. Which isn't to say that the third act was bad. Just a bit too familiar.
I think this movie defined Riddick's personal code of ethics in greater detail than the first two movies. Sure, he kills and steals and generally doesn't care about society's rules for the most part, but he does have a rather distinct moral code, starting with the fact that he doesn't go back on his word. I'd go so far to say that the character is built around his honesty, and it becomes an important aspect of the story in this installment. For me, it's probably the character trait I found most appealing, beyond his general badassitude.
There are two other stars in this movie. The first is Dahl, played by the tough as nails Katee Sackhoff (okay, maybe I should put that the other way around, but I haven't seen her do anything but tough as nails). She had some great moments, a few good lines, and was overall a good character. Only... she didn't feel that necessary. That is to say, removing her from the story probably wouldn't have done much. It also bothered me a little that although she was never a victim, she did feel a bit like an object for the male characters to play off of. Still, I'm glad to see Katee Sackhoff in anything, so no big complaints here.
The other major character wasn't even human. It was an alien dog, and it was probably the best on-screen pet I've seen in a long time. It was cute and ferocious and managed to engage my emotions, which is remarkable, especially considering the creature was entirely digital. The rest of the creature effects were also very good, and definitely a step up from the monsters in Pitch Black. The monster invasion itself was telegraphed from the middle of act two, but it wasn't as if the audience couldn't see that plot device coming.
The remaining supporting cast was decent, but none of them really stood out for me. Jordi Mollà played a really nasty bounty hunter named Santana, and he and his subordinate Diaz (Dave Bautista) were at least fun. There was a cameo from a major cast member of the second movie, and a couple of fun character beats that I won't spoil here. If you've seen Pitch Black, there is a nice character call back to that film, yet most of the cast felt like cannon fodder for the most part. I won't say how many of them die, but there is at least one really cool death that the freaking trailer spoils, so if you can, avoid the trailer before seeing the movie.
Overall, this was an improvement over The Chronicles of Riddick, and I would probably put it close to Pitch Black. As far as an actual rating, well, it's a pretty basic 'R' rated sci-fi action movie. It was fun, had a few great moments, but wasn't what I would call amazing.
2 and 1/2 out of 4 Bald Shiny Eyed Bad-asses That Always Bring Knives to Gunfights.