It’s great macOS High Sierra uses Metal because my MacBook Pro 2014 is now quiet when before the fan started spinning audibly in idle and annoyingly loud under mild load. On the flipside, WindowServer is unstable and causes freezes if the display resolution is scaled. It also causes freezes after some time when external monitors are plugged in/plugged out. Only a restart helps. If my 15" model weren’t so noisy on Sierra, I’d change back to it.