Nope, the limitations are just too huge for actual usage. Heard Godot Engine tried to use MoltenVK for macOS but experienced too many issues so they just developed a Metal backend.

The fundamental problem is Metal 3 is just too high-level to be able to emulate all of Vulkan's behavior. The new Metal 4 API (which is more low level and similar to Vulkan in many ways) might have improved things recently, but sadly MoltenVK hasn't been rewritten to this new API yet.

Worse than OpenGL though? Haven't had the time to really look into it, probably native Metal is better, yes, but either way it might be easier to port/adapt from Vulkan than from OpenGL (due to similar concepts, no global state, etc)