Waves is still under development ... but still allow to trade really fast for a decentralized exchange.
In few weeks the new UI will be released and this will be huge: http://etherdesign.io/project/dex

The DEX is very young, the volume will come slowly when peoples understand that:

• You can trade straight after receiving your ICO tokens
• All your funds are safe because they are still on your wallet
• It's trading almost fast as a centralized exchange