Pretty cool if you ask me. I think Mantle was a success despite what all the nay sayers say. It's objective was to push the industry forward.. Now look at it. DX12 and OpenGL, 2 biggest APIs, now have totally redesigned and pushed the APIs forward. Can't wait to see what they have to offer us. It'll be interesting to see how devs use OpenGL and DX12 when they want to use Windows and Linux for their games.