The 14.x betas have been awful for my all-AMD box (9590/290x)---the one benefit they have (Mantle support) is negated by the fact that these betas all have a bug in them that affects all DirectX games---hitching in places that the 13.12 WHQL are glass smooth. And even using Mantle on BF4 has hitching in places where the DirectX/WHQL combo are smooth.
I just wish they'd get a move on with a WHQL mantle driver. Its been a long time since 13.12.
I had to give up on those betas because on my 7970s crossfire setup they were overheating badly and hanging the system with very high temps. I've rolled back to 13.12 and all problems went gone.