I prefer the three tier system for rating wine. 
 
--Great, nectar in a bottle, good enough to drink every night and with special friends. 
 
--Ok, good  restaurant wine, serve en mass at holiday events. 
 
--Awful, tastes like Jimmy Hoffa marinade. For cooking and deglazing.  
 
The rating scale is needed because there are only so many ways you can differentiat--"f***ing good".