At this moment, there is a live blog here Weekly Tech News Live Stream - PC Perspective about DirectX12, becouse microsoft is showing it to the devs. For now, DirectX12 gives a lot more power to the CPU, its basically a “Mantle-ized” DirectX
“Epic will be working closely with NVIDIA and Microsoft to create a world-class implementation of DX12 in Unreal Engine 4,” said Epic Games’ Tim Sweeney. “DirectX12 is a great step forward, exposing low-level hardware functionality through an industry standard API to give developers more control and efficiency than ever before.”
Well this is awesome.
Here you have proper information about http://blogs.msdn.com/b/directx/archive/2014/03/20/directx-12.aspx
Ok it looks like Microsoft went into panic mode, and ported Xbone version of DX to desktops.
Besides there is no word on what system it will supported so at this point I assume it will be Windows 9 locked.
And more over. Will DirectX12 allow engines to use nearly unlimited amount of unique materials/textures per scene without performance drop ? If not… Then oh well… Move on.
i feel like this is a new era in game developpement world
UE4, CE3 are given to the hands of thousands of developpers around the world,
hopefully we can see wonderful things made with in the near future
it’s a really good feeling 
“Windows, Xbox One and Windows mobile OSes.”
also,
“Nvidia suggested that many video cards running DirectX 11 are already compatible with DirectX 12”
if they were to lock it to Win9 why bother with this?
So if DX12 does not “allow engines to use nearly unlimited amount of unique materials/textures per scene without performance drop” it doesn’t even matter? Honestly, it just appears that you don’t like the Xbox One nor Microsoft.
I personally, am really excited for DX12.