I never really get the hate on Groupon from a business model standpoint, I get it from an execution standpoint but not the business model.

I've derived quite a bit of value from Groupon myself, as have several people I know. They failed in execution because it appears they don't value their relationship with vendors as evidenced by not letting them impose limits in the number of coupons sold. Mom and Pop restaurants don't scale like startups and many were left with really bad experiences from being ill equipped to deal with a massive influx of customers in a short time frame, and consequently the customers ended up having a bad experience as well. This wasn't universal but it seems to have been frequent enough to have severely tarnished the brand. If Groupon had been better stewards of their relationships with their merchants instead of sacrificing them in the name of growth I don't think anybody would lump them into the "ponzi scheme" camp. Groupon could have gone about it differently, Bernie Madoff probably could not have.