Cingular? The Cingular 8125?

I’m getting pretty close to buying the Cingular 8125 cell phone, and, in the process, switching from Sprint to Cingular. Advice or input?

The whole world of “Mobile” is about to get much much more exciting in the US in the next 18 months, and I’d like to be with a carrier and on a device that lets me experiement with as much of it as possible. Is this the carries, the device?

I’m moving from an old Treo (the 600), so it’s also a switch from Palm OS to Windows. Any words of advice in that regard?