Xbox One will not support old Xbox 360 controllers or other devices according to a statement released by Microsoft.
"Xbox One was designed from the ground up with entirely new technology to deliver a new generation of experiences for both games and entertainment For example, the Wireless Controller will connect to the console using high speed data transfer to enable higher fidelity headset audio and future controller add-on experiences that are not possible with Xbox 360 wireless technology.
"Additionally, the all-new Kinect sensor's ability to locate the wireless controller is dependent on new technology. In order for Xbox One to deliver robust, meaningful gaming scenarios for all users across all experiences, only Xbox One controllers and accessories will work with the new console."
We are also hearing rumours that an Xbox headset may not be included this time around as Kinect will be the default communication device, although we can't clarify this at the moment.
In addition to the above, you cannot replace the 500GB HDD, so you'll need to go external if you want more storage space.
On the bright side, you can pre-order the new controller below.