I have been using Restaurant.Com for several years, and never been disappointed. If a restaurant you have a coupon for closes, you get an email, and your credit card gets a credit for original purchase price.
But I joined with all the others, and started using Groupon. My experience with them has not been as good. Purchased a Groupon for $185.00 last year, but before we had a chance to use it, the company closed. Did not know this until we called to make an appointment. No word from Groupon.
We emailed Groupon on the 25th of July, requesting a refund. As of today, all we have are emails from Groupon telling us how well they have communicated with us, and that there were "technical glitches" in giving us the refund.
Do what you will, but I will not spend anything more than I can afford to lose, with Groupon, in the future, if at all.