I'm sort of mixed on how easy Metal is. Having to support Objective-C and/or Swift as part of the build toolchain is sort of a headache and Metal actually isn't low-level enough for me to support a lot of the optimizations I can do in DX12/Vulkan and especially doesn't come close to console APIs (which you'd think should be possible given that they can specialize for their hardware). My feeling is that for driver APIs, it's ok for the API to be lower level since users (and other developers) generally won't need to deal with that anyways.