I've been following Windows Phone 7 for a while. At first, it was the Metro UI that caught my attention, as I had a Zune HD and the similar UI provided really easy and efficient functionality.
Personally, I'm going to get the Samsung Focus for AT&T, as I also really like the OLED screen on my Zune HD, and would like to see it on my phone. Samsung's build quality is really good, and 4 inches, I believe is the sweet spot between 3.5 inches (iPhone) and 4.3 inches (HTC EVO 4G).
Here's a video with some devices, features, and a general crash course in Windows Phone 7.
http://www.microsoft...deoGallery.aspx (The second one).