There's nothing like actually having it run on an actual phone...five weeks of hard work are paying big dividends! Going to run it all day tomorrow to see if I can spot some more usability holes.
As for the Windows Phone 7 device itself, I'm not entirely sure how much I can say about it considering it is a developer phone and not one that will ever reach the market - however, my impression of it is an overwhelmingly positive one. Everything is slick, modern, sexy, and downright fun to use. It's a clean and beautiful phone, and I will definitely be getting me one of these on launch day.