Windows Phone 7 looks extremely promising. There's no doubt that Microsoft has pulled no punches with its new platform (though there still seems to be no cut and paste at launch, but no doubt that will be released in a future update, albeit with less fanfare than when Apple released that feature for iOS).
One thing that's clear is WP7's focus on gaming. Being able to play casual games on your phone, then the full fledged version at home on your gaming consol is a refreshing idea and it's nice to see Microsoft implementing it at launch. I dig my PS3 and while I didn't really enjoy having an Xbox 360 for the few weeks I had it, if I had WP7 device, I would seriously consider somehow getting a 360 again.
Another plus with WP7 is that MS is pushing for some consistency with the OEM's hardware and the software itself (something that Android has been getting flack for).
The device of the future was always been thought to be the "all in one". Your one device to do it all: phone calls, texting, gaming, music, video, general computing, but from the looks of it, MS is setting the stage for the user becoming the entity that connects a handful of devices together and controls how they work with each other. I for one am very excited to see how this all plays out.