I have two restaurants and we have done Groupons for both of them.  Out of all the offers etc, we have tried, these customers are more likely to return and visit us again.  Groupon’s reach is huge and they do a good job of selling the offers.  You get 50% of the offer back from groupon (If you offer a discount of $10 then you get $5 for each groupon sold).
 
We are planning on offering another Groupon, now that it’s been a year.
 
Things to consider.  Be very careful about the amount and the exclusions for your Groupon.  Also, be sure to develop an internal system to make sure people don’t try to use the same groupon more than once–we have a great tracking system and no on has tried, but I am a cynical person by nature.
 
Good Luck.