I'm impressed by two things - the quality of the pizza itself (good crust, great sauce, generous toppings) and the speed of delivery. I thought the prices were completely fair for what I got (I believe it was a $2 delivery charge). I am totally satisfied and would definitely come back.
So why not 5 stars? Well, because it only gave what I expect from a pizza joint. It didn't exceed. I'm looking for a spot that gives me dirt cheap, hand tossed specialty pizzas. That's a 5er. And Pizza Nova? It's cheap, delicious pizza you can shove down your face. No complaints, but only 4 stars.