When I was out at Mix06 I got to play with all the UMPC's that Microsoft had demoed. My favorites are the Founder and the ASUS. The ASUS had slick styling and was nice and thin with a built-in camera, but the Founder had a better form factor and I have to say was my favorite. The controls felt good in your hands and you didn't have to reposition your fingers to do things. This is a win in my book. The others had an eraser nub that wasn't easy to control with you thumb.
Playing with them was very cool and the size was right. The only clunky thing about them was the touch screen. You had to use your finger nail on them to tap the screen. This made the "DialKeys" very hard to use. Luckily the rep at the table stated that this would be addressed closer to production and you would be able to use the pad of your finger instead of your fingernail. The only other grip about them is the screen resolution, I wish it could be higher for a more paper like experience.
However, the coolest thing is that WPF will run on these. Due to the size, vector based content (WPF/XAML apps) are a great fit for these devices. And the addition of pen input will go nicely with the InkCanvas element. It looks like between WPF is going to be everywhere!
Tags: XAML | WPF | UMPC | mix06