We just posted a review of the Audiovox PPC-6601 which is the US CDMA network version of the PDA2K. It lacks a camera and WiFi, but is otherwise the same. It is indeed a very nice unit! The only area it can't come close to competing with the iPAQ is battery life and the iPAQ 6315 runs about 2x longer per charge.
We don't have a review of the PDA2K (aka XDA III) yet because it's not offered in the US. We will likely review it in January since we'll be getting one from Dynamism. But in the meantime, let the Audiovox review whet your appetite .