StellarX is geared to be massively successful as a DEX if the lumens network is functioning upwards 1000 t/x. It will be much more powerful, useful and decentralized than any DEX in existance right now.
In this regard, they stressed that StellarX is not DEX by its very nature but a GUI addon to Stellar's marketplace that allow to trade assets available there. Anyway I fully agree that StellarX being the first full-featured trading addon for Stellars marketplace is an achievement of utmost importance.