Vin Diesel is some form of badass shiny eyed alien who for reasons that are kind of complex is left on a barren planet, full of cgi beasties and sand, and he must find a way to survive when some bounty hunters come looking for him.
Actually the best bits of this film are the Vin vs Planet scenes, in which Vin fights his way through some actually dead cool looking aliens. It is shot nicely, and I really like the colouring. But primarily these are the best bits due to the lack in dialogue. And as soon as other characters enter the picture it really loses its way horribly.
Riddick himself is the only well-acted character (I actually really rate Vin Diesel), and he is also the only one with any depth whatsoever. But the real problem with Riddick is the portrayal of the sole female character, which is downright monstrous. Having a female character who is good at fighting is great, but you don’t need to make her a lesbian, just so the viewers feel what, less threatened? Because it’s not ok to get beaten up by a woman, but it’s alright if she’s a lesbian? What? And then there is the “humour” which frankly is an abomination, with its horrible sexuality jokes, and just plain not funniness.
Overall Riddick was a real disappointment, because it starts well, and then carries on well for about 40 minutes, and then for the most part continues well just with awful character writing and shameful attempts at comic dialogue.