Based on QEMU+KVM so it's quite robust. It works pretty well, plus it has various little features working out of the box that in some other software is a pain in the arse to configure.
Sticks out a bit on my system due to still being GTK3, but there is a GTK4 prototype out that usually works well.
E: downvoting anybody who says Gnome Boxes because you use a different virtual machine frontend is laughably pathetic lmao. Some people in the Linux community are such losers lol