It's a UNIX box, man. The most
(programmer-)friendly OS in
existence. At least for even moderately technical
people.
There are UNIX-compatible people and non-UNIX-compatible people (cf
Unix Hater's Handbook).
Even aside from that, I'm not convinced. I think Symbolics Genera is
arguably more programmer-friendly, though that could just be because I
find Lisp a much nicer language than C. (There may be even better
OSes; that's just what I have personal experience with.)
This message pertains to der Mouse's comment... Out of idle curiosity I
looked up Symbolics Genera and the story of the Lisp machines...
Fascinating! Any idea of how to get one's hands on such a machine?