Not useful must be a subjective experience. I make more money on DEXs than any other exchanges, no question about it. I also get assets at much lower prices than most CEXs....then I go sell them to the CEX people who will pay more for them. I'm sorry you've had that experience. I will say if you're looking to day trade all day, that's probably not the best place to do it, but otherwise I see the BTS DEX as a huge advantage over trading on CEX. Prices might be higher at times, but generally I get a better deal with a little patience, and the price always levels out to normal if it is high or low.

And shoot, the other day Kraken and Bittrex BTC prices varied by over $1000.