First, OpenCoin pre-mined the XRP's so they could hack the cryptocurrency trend and make tons of money if their currency took off.
Second, Ripple is NOT a decentralized currency, but in fact a "distributed" currency, which is actually a much bigger deal than you might think. This means it has a single point of failure, can be easily abused by the creators, and is extremely vulnerable to intervention by governments and other big players.
(You can read all about it here: http://ripplescam.org/)
Bottom line: the strength of a currency depends almost entirely on the trust in that currency, and I have no reason whatsoever to place trust in ripples. It's a wiser move to put your money in a non-scam currency, like Bitcoin or Litecoin.