How bad is it? It's like a really bad drag show.
Should you see it? Not unless you're a huge fan of drag.
There are some really good drag films ("Priscilla, Queen of the Desert" being the best), but this one is not one of them. The plot has two men sent to a female only planet and to disguise them, they take a pill that changes gender. the whole joke is that every character that's supposed to be female is played by a drag queen. [Technically, that's not quite true, as there's at least one post-op transgender actress.] Vegas in Space is the name of the capital city of the planet Clitoris (yep, it's just that clever), where most crimes are crimes of fashion. What's supposed to be humorous I found annoying.