Well I think that if you use a simple Buy it/Rent it/Avoid it system, it doesn't convey what you mean and can lead to confusion.
This review for example. Fallout 3 is a game that cannot be rented, because of the amount of things to do. But suggesting "buy it" implies that I support it a fairly good amount because it is the highest thing I can say. I much more like the idea of a closing paragraph, because it can sum up things much more than numbers and 3 option systems. I hadn't thought of it, so I didn't include it over the numerical score. But thanks for your feedback RAKtheUndead, I'll start doing closing paragraphs instead for any future reviews.