If you visited Microsoft's Xbox One Pre-Order Product Information you may have noticed three items in particular amongst its various requirements and restrictions:
Basically it means you can't join in on a class action suit against the company if you have some disagreement. If you do have a complaint you will have to go before an arbitrator - which is hired by Microsoft to help settle disputes.
Of course it should be noted that this is the standard thing to do when it comes to class action lawsuits: Sony, Steam, and many other companies are doing the same thing.
The page also lists which regions Xbox Live will be available in at launch and that the games you buy in a particular region are only playable in those regions (in other words, the system is region locked. For those keeping score, the PS4 is not).