Is it possible to either filter or at least review Netflix movie downloads based on criteria like movie rating, nudity, obscenity, violence, etc?
Yes and no. There are some options available. If you're looking at a movie's description, you can see what "kind" of a movie/show it is (this is under This Movie Is:). You can't get anything closer to what you're asking for but I usually use that as a pseudofilter.