I've used Crypto-Bridge recently, and that's part of the general BitShares based decentralized trading network. It is clunky and difficult to use. So yeah, not ready for the prime time. It's definitely good for DMD to be on these decentralized exchanges now. Just know that they are currently a turnoff to many people who just want to be able to conduct their cryptobusiness in a simple and streamlined fashion.
I have tried using Crypto Bridge too. As my own experience, this exchange is hard to use (as you said), and transaction fees are too higher (much more higher than other exchanges). Nevertheless, decentralized exchanges might be new hot trend this year or several coming years. Decentralizing is key point in crypto ecosystem, hence exchanges should and will not be exceptions.
It might be better if Diamond project will have its own decentralised exchange.