Not a scam, but they missed the point of Bitcoin : it's peer to peer. no central server, can't be shut down.
Ripple is the new Flooz / Beenz . Same fate to be expected.
Supposedly they have designed it in such a way that a number of servers can be run, making it somewhat decentralized, thus avoiding the fate of the old centralized failures. If they actually come through with their promises is still yet to be seen.