I use Gnome Shell (3.18) with a HiDPI display and everything works great out of the box (except for Steam).
My only complaint is that I haven't figured out a way to have a different scaling factor for each screen, so when I attach multiple displays with significantly different pixel densities one of them ends up way too big/small.
My only complaint is that I haven't figured out a way to have a different scaling factor for each screen, so when I attach multiple displays with significantly different pixel densities one of them ends up way too big/small.