Microsoft have only released limited information on how this sharing will work but it's potentially very interesting. It could mean that you can get access to a lot more games (with some restrictions) if you have other XBox One owners in your family or friends.
Update: Microsoft have pulled this feature and returned to sharing via physical media. This is in response to a an outcry by traditional gamers who aren't ready to move to digital games yet. I think that's a shame.
"You can always play your games, and any one of your family members can be playing from your shared library at a given time." MicrosoftWe're still lacking the full details of how this sharing will work. There will be a limit to multiple family members playing a game at the same time. One interpretation of the statement is that the owner will always be able to play a game even if one other family member is playing it at the same time, but this is far from clear. What about multi-player games? Will you be able to play with a family member if you only have one copy of the game between you?
"they don't have to live in the primary owner's house—I could name a friend that lives 3,000 miles away as one of my "family members" SourceArs Technica spoke to Microsoft's Yusuf Mehdi and got a little more detail - it seems that the family members won't need to be blood-relations and nor do they need to live in your house. It looks like you'll be able to give 10 close members of your network access to your games.
Is the owner included in the ten family members? What about all the players in the owner's home? (Anyone in the owners home gets access to the games anyway while they are in the house, but what about when they are elsewhere?)
There's been a lot of focus on the negative aspects of moving gaming to digital ownership rather than physical disc-based ownership, but it's inevitable that this is going to happen and it does enable new sharing models.
I'm interested to see how this plays out. There could be a lot of incentive for families who know others with an XBox One to also get the same console so they can share games and get access to a wider library of games at a lower cost.
We'll have to wait for more details on how the sharing will work and whether there will be barriers that we don't know about yet.