Which Unicode characters can you depend on?
johndcook.com
johndcook.com
My favourite fonts Inconsolata and Adobe Source Proc support barely anything beyond latin1. So I usually end up with some ugly font mix due to fallback.
(Of course if you want all of Unicode and hate yourself there is GNU Unifont. edit: Just checked and Unifont only supports all of BMP.)
https://dl.dropboxusercontent.com/u/390716/20130412-003357-d...
https://dl.dropboxusercontent.com/u/390716/20130412-003523-d...
http://unifoundry.com/unifont.html
Terminus is nice, too, I suppose:
http://terminus-font.sourceforge.net/
http://terminus-font.sourceforge.net/shots.html
Inconsolata is popular:
The main problem was Apple products, surprisingly. It's crazy the iPad and iPhone don't have better Unicode support!
It may not be the case on mobile, but it appears to work this way on Windows and Linux.