“This one's supposed to be good.”

You're at a video store, looking for a DVD to rent for the weekend. You see a movie that you read a positive review of. You want to convince your wife to watch it, so you say:

This one's supposed to be good.

(something) is supposed to be (adjective)

When you hear or read information about something, you can report that information to other people with the phrase "___ is supposed to be ___". Some examples:

The steak here is supposed to be amazing.

Tokyo's supposed to be super-expensive, isn't it?