Just for the record, this means ethereum contracts ( wallets ) can hold any token shapeshift supports. Like, you can hold bitcoin in your ethereum wallet by using prism. If you buy a token, say dash, you won't have to use a dash wallet aswell, or worse, hold it on exchanges.
You know the old bitcoin maximalist saying "one blockchain dominates them all. I think we can adapt it and say "ethereum wallet dominates them all.
Actually, this does not mean that at all. Say you make a "prism" of 1BTC. Shapeshift will then charge you a 2.5% fee and then a 1% fee every month (close to 12% annually) to "manage it." what happens behind the scenes is Shapeshift buys 1BTC and holds it. When you close your fund they convert it into ETH (using accounting techniques, not blockchain transactions) and send the ETH to you.
The counterparty risk they don't tell you about is if shapeshift goes bankrupt you can't redeem your investment.
There are more issues with this, find out more-
https://steemit.com/cryptocurrency/@pawnuts/why-shapeshift-s-prism-is-a-scam