From a technical standpoint, DX12 is a considerable improvement. It makes much better use of the computer's resources. From a programming standpoint, it's also very interesting, reminiscent of OpenCL and AMD's Mantel.
And there's a start button with a proper desktop. Thank Christ.
Window 8 was designed around tablet and phone interfaces that focus on maximizing consumption of screen real-estate for single programs. Thus, Windows had to go, and everything had to be consolidated into one window at a time.
Well - you could kinda-sorta break away from the Metro UI on the PC... but... meh
At least they seemed to build a proper UI this time around.