I tried X2. Its a child's toy and is not even direct access. Why wouldn't you use C.Trader pro? Pro is much better and is direct access. Just my .02.
I don't use it myself, but my firm just linked our analytics to it and I am curious what people think about it in general. The more feedback the better.
X2 is a bit flashy like Ebo mentioned and wastes a lot of screen space. You can use QuoteTracker as a trading platform with the X2 account to get a better trading interface without having to upgrade to Pro account.