Well, I've been playing around with all kind of umpc's: starting with HTC Athena (X7500), going through UX180p, then UX380n and finally the HTC Shift (x9500/Shangrila). The finest from all is no doubt, the UX380n! But, in matter of working daily with (office, internet browser, adobe), the Shift is the one that beats all the others. I don't really understand (maybe costs matter and even so, a more than 1000€ at the time of release was already too much for such device) why HTC didn't assemble a Core Solo Intel! Even for UX series (and they are faster than any other umpc on the market at this time) the Core Solo is not for Vista / W7! And, the battery life on Shift is simply a joke (less than 2 hours on Vista/W7 side)!
Overall, even with the power horse of UX and the cons on the Shift, I have to stick with HTC; it has the keyboard (a very good one, instead UX's keyboard is a joke), it has GPS capabilities, it has PHONE (just put a SIM and you're good to make phone calls and access internet), it has SD slot and it has WinMo side (even sometimes I see this second OS as being useless).