I don't see how you can give this place anything less than three stars. Three if you think the pizza is horrible, four if think it's decent (hence my four stars), and five if you think it's great!
This place is just such a novelty at the Cosmopolitan. Like others have mentioned, it's hidden away amongst all the other restaurants on the third floor, with no signage, and I think no actual to name to it. You probably wouldn't even eat here unless you're drunk (which was the case w/my two trips here on a debaucheries LV weekend) or broke (this is definitely the cheapest food you'll find in this hotel).
Like I said, i thought the pizza was decent. Of course I was drunk on night 1 when I devoured a slice of cheese & on night 2 when I had some sort of Greek style pizza (it had gyro meat & feta). They seem to churn out pizzas pretty quickly & there are several varieties to choose from at any given time.
They also have two beers on tap (one is Pabst and I forget the other one, but it's something cheap) as well as fountain soda, which sounds FANTASTIC at the end of the night. Both are served in those AWESOME red SOLO cups synonymous with kegs.