[mgberlin]

Ripple has written a compelling implementation. It can handle massive transaction volume, is building a network internationally with established banks, is slowly releasing more currency into the wild resulting in inflation, and is pre-mined to avoid having to do proof of work.

[jeremyt]

Ripple, while interesting, isn't designed to be crypto money, it's designed to be a global settlement network, which is the first thing you'll see when you go to their webpage.

Furthermore, their transaction costs are currently at a minimum an order of magnitude more than what a Bitcoin transaction costs, running to 2-3 orders of magnitudes. It's a replacement for the SWIFT network, which is all great but not really directly competing with Bitcoin.