I stopped by the Sprint store yesterday to check out the HTC Touch and thought I'd post my thoughts.
1) The form factor is EXCELLENT! It's much smaller than my Treo with curves and soft-touch paint that make it feel really good in the hand. I was shocked at how small it was. This is something I could forget about in my pocket.
2) The screen was bigger than my Treo's screen, and I liked it. However, it did pick up a lot of glare; but this could probably be fixed with the right screen protector.
3) There are hardly any buttons on this device so you are literally expected to operate it with your "touch." I'm not sure how well Windows Mobile 6 is set up for this. The screen is flush with the front instead of recessed like other touchscreen devices so that should help. I didn't get to use it long enough to get a good feel for the screen sensitivity. It was certainly fine with the stylus.
4) I am just unsure of using a device like this without a physical keyboard. I didn't like the on-screen keyboards that HTC had included. Perhaps a 3rd-party solution like http://www.cootek.com/ might make it more usable. Just hard to say without using it for awhile.
I'd love to test drive a device like this for awhile. It certainly made me realize how much of a brick my Treo really is. The Touch is new, stylish, and compact. The Treo looks very dated next to it. I can't wait to see what else is released in the next few months. I think this device is on track but I'd like to have a physical keyboard, WiFi, and GPS as well. The HTC Touch Dual will at least add a keypad.
UPDATE: I stopped by the store again to have another look. I still love the form factor; however, I really don't know that I could get used to a virtual keyboard. I played with it some and even installed TouchPal from Cootek.com and just wasn't happy at all. Perhaps if I forced myself to use a virtual keyboard for a couple weeks I might adjust. It just seems to rely too much on predictive text and that makes a lot of mistakes.
Also, the screen has issues. It is very reflective and can be hard to see in the glare. Also, I noticed that it has trouble with the vertical angle which gives that negative image look. Therefore, when you use the landscape mode you can get a bit of a double-vision look to the screen. I liked the screen on the Mogul much more.