Last week saw the release of the final version of VS 2015, and yesterday was the release of the Windows 10 SDK (10.0.10240). The Windows 10 SDK is installed via VS 2015 Custom install options or as a standalone installer. This includes DirectXMath 3.07, Direct3D 11.3, Direct3D 12.0, DXGI 1.4, Direct2D/DirectWrite 1.3, and XAudio 2.9.
VS 2015 Users: Be sure to read this blog post about configuring your VS 2015 projects to use the 10240 build of the Windows 10 SDK--remember that Windows desktop applications with VS 2015 default to building with the Windows 8.1 SDK Spring 2015 release.
Direct3D 12: The samples for Windows desktop development using Direct3D 12 are on GitHub. Note that WARP12 is part of the Graphics Tools optional feature as it's currently intended only for use by developers.
XInput: For UWP, you can continue to use the XInput 1.4 API but need to change from linking to
xinputuap.lib. Alternatively, you can make use of the GamePad class in DirectX Tool Kit which uses the new
Windows.Gaming.Input API. See XInput and Windows 8.
XAudio: With the Windows 10 SDK, if you are linking with
xaudio2.lib you are linking against XAudio 2.9 and should build your application using
_WIN32_WINNT=0x0A00. If you want to use XAudio 2.8 with the Windows 10 SDK, you need to set
_WIN32_WINNT=0x0603 and link against
xaudio2_8.lib. See XAudio2 and Windows 8 for more details.
VS 2013 Users: As with the past few releases, the Windows 10 SDK only integrates with the latest Visual Studio, VS 2015. You can use the Windows 10 SDK with VS 2013 by using the props attached per this Visual C+ Team Blog.