Microsoft has released SQL Server 2016 RTM CU3 (Build 13.0.2186.6), with 31 fixes in the public fix list. They have also released SQL Server 2016 Service Pack 1 (Build 13.0.4001.0).

As they previously did for SQL Server 2014 SP2, Microsoft has managed to include all of the hotfixes from the latest SQL Server 2016 RTM CU3 in SQL Server 2016 SP1 RTM, including the very recent security fixes in Security Update MS16-136, so there is no need to wait for a subsequent SP1 CU to get caught up with the latest fixes from the RTM branch.

The Microsoft SQL Server Release Services Blog has a lot more detail about SQL Server 2016 SP1 here. The Data Platform blog has more detail about SP1 feature improvements here.

Given all of the feature changes and other useful improvements in SQL Server 2016 Service Pack 1 (on top of all of the hotfixes), it is almost a no-brainer to move to SQL Server 2016 Service Pack 1 as soon as you can do your testing, and plan and implement your deployment.

This is also a good time for organizations that are running down-level versions of SQL Server Standard Edition to seriously consider upgrading to SQL Server 2016 Standard Edition (preferably on new hardware, running Windows Server 2016).