Holy moley, but it's good. The phone feels nice and zippy, and there are some UI enhancements which are nice.
But it's the apps that I was interested in. Kindle for Android, Google Maps, Google Goggles, etc.
Google Goggles is astonishing. Take a photo of a dvd, and it scans it, recognises what it is, and offers you shopping, imdb or the wikipedia page for the film.
google maps also now has turn-by-turn navigation! woo! free satnav!