Ripple is definitely promising - but it still relies on gateways to get fiat into their database; none of which are currently operational right now, presumably because Ripple is wading through the logistical morass of operating a currency exchange.. Certainly more players cant hurt.
Holding IOUs from a gateway and transfering it to or trading it with someone else is conceptually the same as holding balance at MtGox and transfering it to someone as a redeemable code or through a transaction on the exchange. The major difference is that, in the case of MtGox, you are stuck having to use their crapy Php plateform, and jumping in AML/KYC hoops, and exposed to leaks and stealth of your funds, whereas in the case of Ripple, you rely on the built in distributed exchange mechanism written in C++ by much more competent people, you are known only by your wallet's public key that is pseudonymous, and your funds are secured cryptographically like with any cryptocurrency.In the future of Ripple, MtGox will likely be reduced to acting as a gateway, handling the paper work, and issuing IOUs, which is perfect because MtGox's strong point is the variety of payment and withdrawal methods they offer and their compliance with legal framework, and their universally admitted weak point is trading technology, which is what Ripple proposes to handle on their behalf.
