You probably will have to run the Listener and use its Browser to go through the documentation to see how awesome it is. That, or just look around here:
The first link might give the wrong impression about Factor not being low-level, but it definitely can be if you want to; after all, its optimizing compiler is written in Factor itself!
https://concatenative.org/wiki/view/Factor/FAQ/Why%3F
You probably will have to run the Listener and use its Browser to go through the documentation to see how awesome it is. That, or just look around here:
https://gitweb.factorcode.org/gitweb.cgi?p=factor.git;a=tree...