You can also see from the Leaderboard where your Restaurant is in the worldwide ranking and also how your Restaurant is ranked against your friends.
To check how you are getting on, tap on the Popularity bar at the top of your screen.
Here you can see you Restaurant's current Star rating and Level, and how many Popularity points you will need to progress to the next Level.
There are 9 Popularity Levels displayed as Stars, these are:
Bronze Star - Levels 1, 2, & 3
Silver Star - Levels 1, 2, & 3
Gold Star - Levels 1, 2, & 3