[ghaff]

That's part of the problem here. Appropriately rating different types of things differ in various ways.

A simple utilitarian object? It mostly works or it doesn't.

A movie? Just to start with, there's the rating of the movie itself vs. the rating for this particular DVD. And then there are the dimensions on which the movie itself could be rated.

Or you just throw your hands up in the air and either do a thumbs up/down or a 5 star rating system on the grounds that it's better than nothing.