I'd say sound quality is very hit and miss. To be fair, DW are better than most and are always improving. As Static14 said, coloured vinyl is inherently unpredictable, that's just how it is. Sadly, a lot of people who've jumped on this soundtrack craze are more concerned with how records look than with how they sound.
If you're worried about sound quality but still want coloured wax, then avoid the splatter/marbled editions and stick to the solid colours or transparent editions.
It never fails to amaze me how many people buy crazy coloured vinyl and then complain about the sound. I mean, what do you expect? There's always a compromise with these things, that's just how it is.