The math examples look interesting, standard math notation and all. Though if I got it right, you get standard math notation with the help of TeX when viewing source code, I'm not sure about editing source code (I sure would rather write Matlab or numpy notation than use TeX in source code.)

Where are other biggish examples?

The "styles" page has the biggest bulk of interesting code that I've found in introductory pages: http://felix-lang.org/share/src/web/advocate/styles.fdoc

I guess one always wants to hear an elevator pitch of what a language does that is special relatively to relevant competition. What does Felix have that languages X and Y, its closest competitors, don't have?