There is a website setup specifically for my university that is much like this. It's OK but there are a lot of people posting bad reviews just because they received a poor grade.
The only overall ratings I really pay attention to are especially horrible ones because in my experience they are probably accurate.
"Cheshire Puss," she began, rather timidly... "Would you tell me, please, which way I ought to go from here?"
"That depends a good deal on where you want to get to," said the Cat.
"I don't much care where..." said Alice.
"Then it doesn't matter which way you go," said the Cat.
Alice’s Adventures in Wonderland