Nope. This is not a one hand phone. I was used to the ease of one handed use with my Blackberries, so when I switched over to this phone it did sort of frusterate me for a little while. But like anything else you get used to operating it with two hands. During those times when I HAVE to use one hand, I flip it to portrait. That's the only way you can do it one handed unless you have hands like Michael Jordan or something. But for me anyway, the portrait keyboard seems less accurate. I always get mispelled words on the portrait keyboard.
If one handed use is a priority for you, well to be honest then the DX might not suit your needs. One handed use just isn't one if it's strong points.