I use Arch Linux, and have instaled ttf-google-fonts-git. Roboto has always been a part of the package. But the site still looks awful on my computer. When I was typing this as a comment, I couldn't see what I'm typing well enough. Though I can see this just fine when typing in the Answer section. 

If you must use Roboto, please use Roboto-Medium or Roboto-Regular instead of thin or light variants. The site is currently unusable for me. And please set up fallbacks for people who don't have Roboto.