If you're planning on playing your Xbox One tomorrow (July 18,) you should be aware that Microsoft will be performing scheduled maintenance. This will impact certain Xbox 360 titles and services, including backward compatibility.
The maintenance is scheduled to occur between 2:00 PM UTC and 3:30 PM UTC (10:00 AM ET and 11:30 AM ET.) Between these times, you might notice issues with Xbox 360 backward compatible titles on Xbox One. Xbox One titles and services are not impacted, but if you're playing Xbox 360 games, you might be disconnected from Xbox Live one or more times.
If at any point you're concerned with the status of Xbox Live, you can always check in by visiting this Microsoft webpage. Maintenance is routine and only helps make Xbox Live a better service.
In somewhat related news, Microsoft just announced two new backward compatible titles on Xbox One---Dante’s Inferno and R.U.S.E. The second half of this month's Games with Gold Titles also just became available, including both Death Squared and Splinter Cell: Conviction.