Some of the Xbox One accessories are released and I picked up my extra controller today. Impressions as compared to the 360:
I like it
Fits in the palm
It feels like it fits my hand better. It really snugs into my palms well.
Triggers feel more natural
The triggers seem a little closer, as in, they are further away from the tips of my fingers (if that makes sense) and feels more natural to me. They also have less spring back force (put another way, it pushes back less).
Buttons are similar
Likewise, the buttons seem closer to my hand; my thumb extends further over them. The button presses feel almost the same. Buttons seem a touch closer to each other.
Thumbsticks feel smaller and taller
The thumbsticks have a smaller diameter but seem a bit higher, which should give you a bit more control. Hard to really say if these are better until I'm actually playing.
Bumper / D-Pad clicks like a mouse
The bumpers and direction pad feel like harder clicks than before, more like a mouse click. I'm not too sure I like this but it seems responsive across the bumpers.
All in all it feels very natural to my hands.