Gnome 3 is pretty close for HiDPI. So all of the default applications look great. It's still a bit of an issue that Chrome and Firefox are almost unusable so I've been using Epiphany and liking that.
In Chrome you can set the default zoom for pages, but you will have tiny tabs.
Until you connect a non-HiDPI external display, where everything will still be scaled up by a hilariously huge factor of 2.