From Zagat.com:

Quality, Presentation and Service are each rated on a scale of 0 to 30.

26-30 ...extraordinary to perfection
20-25 ...very good to excellent
16-19 ...good to very good
10-15 ...fair to good
0-9 ...poor to fair

For places listed without ratings, such as a newcomer or survey write-in, the price range is indicated as follows:

VE ...Very Expensive
E ...Expensive
M ...Moderate
I ...Inexpensive