For $9.99 a month, Xbox users can download and play a select number of Xbox One games from a rotating catalog that changes monthly. In short, it's Netflix for gaming and minus the hassle of waiting on the mail or returning discs to an automated kiosk. In addition, Xbox Game Pass subscribers will receive special discounts on DLC and other games not currently part of the Xbox Game Pass catalog. Of course the $9.99 price tag is in addition to the cost of Xbox Live, which is also $9.99/month.
It will also be interesting to see if the $9.99 price tag also includes a subscription to EA Access, a similar service that's only available on the Xbox One and restricted to only EA titles.
Xbox Insider Program members have access to the program now while a full-scale rollout will occur sometime this Spring barring any major setbacks.