It is either a scam or very poorly coded. I've seen one transaction in the blockchain for 7BTC from yesterday that hasn't been paid. But, people sending 0.01BTC today are being paid. Any proper Ponzi scheme would pay back in time order, not by order of value.
I found this at https://bitcointalk.org/index.php?topic=447831.80: "Actually, I set it up to prioritize the small transactions. The 1 BTC depositor will have to wait a while, and everyone else will get paid out as soon as their transaction confirms (this makes sense since the 1 BTC guy is making more money anyway)." Clearly doesn't understand the concept.
