VS 2015 Update 3 was released over a month ago. While its release notes mentioned some STL fixes, here's a comprehensive list.
 (Previous changelogs: RTM Part 1, RTM Part 2, Update 1, Update 2 features, and Update 2 fixes.)
 STL Features
 /std:c++latest enables the following new features: P0025R1 "clamp()", P0185R1 "is_swappable, ...