Looks like some of the big sites managed to get a hold of some tester Windows Phone 7 devices (luuuucky!) and the consensus overall seems to be quite solid. The hardware is a Samsung Taylor SGH-i707 with 480 x 320 (HVGA), which is a bit odd although reportedly it looks really good. The Taylor also has a 5MP camera, speakers plus microphone on the top and bottom for both and a non-functional front-facing camera. There's even a dedicated camera button that works if the device is locked.
Engadget points out the great on-screen keyboard, camera and even browser, and finally concluding that WP7 is a work in progress, a promising one, but not quite there yet.
Paul Thurrott also does a fantastic tour of the device and is quite impressed with the OS. Although we have to experience Windows Phone 7 vicariously through him, we usually agree with his insight and highly recommend the full read.
There's also Matt Miller of ZDNet (and of Nokia Experts) who has a nice 8-page review, concluding that the "...current experience is amazingly stable and fluid and I am quite impressed with what they have done".
Anyways, we'll let their reviews stand for themselves. Read 'em and comment back here if you're more or less excited now.