After years of using Symbian, I've just switched to a WinMo 6.1 device, to wit, a brand new HTC Tytn 2. My P910i, whilst still as reliable as ever, was being left behind by the inexorable march of progress.
The new OS is a fairly steep learning-curve, despite having had Windows on numerous PCs ever since Windows 95. I've played with WinMo on borrowed handsets at times, but am now really coming to grips with it. I'm pleasantly surprised as to how intuitive its turned out to be. The logicality of the system is good for anyone used to Microsoft's desktop operating systems, and offers a far higher degree of configurability than Symbian.
So expect me to pop up here from time to time with enquiries about tweaks and tips!
George