Plan9's underlying "everything is a filesystem" paradigm is wonderful, but as a hardcore user of vim/emacs and fan of tiling window managers like i3, the mouse-centric Rio/Acme interfaces seem to be pretty clunky and inefficient.
Its C-inspired programming language is also pretty primitive. I'd much rather have seen it built around scheme, lisp, or even a modern statically-typed language like OCaml, Haskell, or SML.
Its C-inspired programming language is also pretty primitive. I'd much rather have seen it built around scheme, lisp, or even a modern statically-typed language like OCaml, Haskell, or SML.