Sorry I didn't get back to you yesterday. I have used them once and the restaurant I chose, I didn't use the certificate right away so when we went they were no longer participating in the program so it was a bust. But restaurant.com did issue me a credit towards another restaurant. I have read several reviews from people that say they work, others say they don't, so its a crap shoot. I think the key is to use them relatively quickly-like before the end of the month. The restaurant chose to be in the program so they should honor it at least for that month.
And most restaurants terms say they will not accept more than one certificate from a table.
I know its not a GREAT review for them but I thought I would give them a second chance to see.