I have used Groupon for discounts on local services and have found it to be very good. BUT, buyer beware - groupons for services expire in 180 days. You don't lose the money you paid, you lose the deal. But, the reality is, can you expect a local vendor to hold up a deal for longer than 180 days? I guess not.
My experirence with buying goods has been with buying a refurbished phone. I'm on try #3 because the first one came in and the speaker didn't work. Second one came in and wouldn't accept my SIM card. My biggest gripe with Groupon - it takes 2-3 weeks for the refund, even if I return the item immediately. Groupon's customer service is nothing special and it's impossible to actually speak with someone - the best I could do was a chat and the person was of no help.
I am an avid Amazon.com user because their return policy is AMAZING and their customer service is excellent. If this third phone is not good, I'm done with Groupon - I'll spend the extra $$ and buy from Amazon.