Over forty improvements have been made on the Xbox One
controller over the Xbox 360's and here's a 7 minute video detailing some of the changes brought forth by Microsoft.
Some of the bigger highlights include haptic feedback in the triggers, an improved D-Pad, an IR transmitter on the front of the controller, and a standard microUSB connector. They had a great deal of models and feedback from focus groups to try and make this the best controller out there in feel and performance.
I've been a fan of the 360 controller and I still used a wired one with my Steam box. This one looks like a nice evolution of the 360's controller and I'm wondering if the microUSB interface will let any of the controllers to be used on the PC as well.