Riddick had interesting production design, but was hamstrung by an absolutely horrible actor in the main villain slot; Sean Bean probably could have been had within their budget, and would have rocked that role without upstaging Vin.
Karl Urban was also surprisingly lame in the movie.
I finally saw Pitch Black the other day, and was truck by its average-ness. It's a B-movie with some decent effects for its day. In that sense, it's like Tremors, but Tremors is a far superior flick.