My personal experience with OpenGL is that all Valve games run faster on it than on DirectX (both on Windows, but I heard Linux + OpenGL also has better perf than Windows + DirectX), but that's about the extent of it.
My personal experience with OpenGL is that all Valve games run faster on it than on DirectX (both on Windows, but I heard Linux + OpenGL also has better perf than Windows + DirectX), but that's about the extent of it.