I've been running macOS on both my XPS 15 (9550) and desktop (Haswell i3 based w/ Nvidia graphics). The experience is good on both systems but they definitely have their caveats.
The XPS is probably the most positive experience thus far, it'ss a 9550 with i7/16GB RAM/1TB NVMe/GTX 960/4K. It's currently running Mojave 10.14.3, everything except the SD Card reader and Nvidia GPU work (including the touchscreen, WiFi OOTB, Bluetooth, etc.). The GPU really isn't a problem, Intel graphics work with full acceleration and anything GPU-heavy gets done on the desktop. Helps with battery life too; my system's battery health is down to ~45% but I can still squeeze out a good 4 hours from it. It's not very well supported, you really gotta stay on top of updates and be ready to fix what breaks, but when it's running it's a dream to use.
The desktop on the other hand is a completely different beast. It's got an i3-4150/8GB RAM/GTX 980 and currently running High Sierra 10.13.6 (because of a lack on Nvidia drivers in Mojave). Getting it setup was a little bit of work, the WiFi/Bluetooth card needed an enabler kext and audio needs a bootloader tweak to work, otherwise it's functionally indestinguishable to a legitimate Mac; It can even be updated through the Mac App Store, iCloud/iMessage works, Handoff works.
I personally wouldn't build one again. I've built 4 in my life and my last one was High Sierra (last year is when I stopped using it).
It'll run great (NOT problem free) for 6 months; just enough time to forget everything you learned over the entire weekend you dedicated to initially getting it working, then update or something will break and you have to dive back into the tonyx86/etc rabbit hole for another entire day or an entire weekend.
Look at what he said, it's great when it works. That's the problem.
Stuff will usually still "work" but your video drivers will drop your resolution to 640 and you have to fight with that and try new kexts, sometimes your sound will flake and you'll research how to fix it, etc.
If your time is remotely valuable and you want your personal equipment to just "work" and not have to be tinkered with it's unpleasant.
That's why I was so excited the Mini finally got updates, but that doesn't really work with egpus so I wound up just going back to my MBP.
