1. Price and availability
The Xbox One will be released in Australia on November 22, and will cost AU$599. The Kinect camera is included; you can't opt out of that peripheral.
2. You'll need an XBOX Live subscription
You'll need an Xbox Live Gold membership ($60/year in the US) to do almost anything beyond play single-player games.
3. It will play Blu-Ray, DVD format, and CDs
The Xbox 360 only had DVD support. The Xbox One now plays Blu-ray discs but not the new 3D Blu-ray format.
4. The Hard Drive is not replaceable
The hard drive is not user replaceable as the Xbox One comes with a 500GB hard drive. The Xbox 360 used to have a proprietary snap-on hard drive; on the One, it lives inside the console.
5. It will not play your old Xbox 360 titles
Bad news for Xbox 360 owners with huge game libraries: the Xbox One won't play your discs. But why would you want to play them? The newer graphics on the Xbox One will probably make you want to play the newer titles.
6. The Xbox One is bigger than the PlayStation 4
The Xbox One is a bulkier console, with a very large power supply adapter in comparison to the PlayStation 4 with its regular thin plug.