I was lucky enough to get my hands on this beaut at E3 this year and I gotta say, I fucking loved it. The sticks felt looser yet more responsive as I had just played Diablo 3 on 360 and then almost immediately went over to a play Killer Instinct; not the best comparison of course but a comparison none the less. Loved the flat feel and screwless design; it's crazy how much you can take the subtle things for granted.
This video has Xbox Live's Larry Hyrb give a tear down of the outer and inner parts of the new controller you can expect in your shipment of next gen goodness. I have to admit I've been really intrigued by the rumble in the triggers since it's announcement at E3 but none of the games I played showed any sign of it's implementation, or how exactly it could be used.