I'm a fan of 4 stars, as I think it forces you to make a real choice, while still being simple enough that it's hard to misinterpret: 4 stars => great 3 stars

I'm a fan of 4 stars, as I think it forces you to make a real choice, while still being simple enough that it's hard to misinterpret: 4 stars => great 3 stars => quite good 2 stars => not so good 1 star => bad There's no score right in the middle so you can't sit on the fence (unless you ruin it by allowing half stars, Ebert style).