[hashkb]

It is significantly more powerful. With key bindings you control or scripts you write, you can move/split/combine your tabs/panes/windows in any way you can imagine, which for me is more ways than iTerm allows.

Ever SSH into the same machine twice? Put tmux on your servers. Or use it to leave jobs running and check on them later.

Edit: Almost forgot. If you use a console editor like Vim or Emacs (well, Emacs people probably do this all inside Emacs) you can basically build-your-own IDE by running arbitrary code in tmux panes (again, your imagination is the limit here) or send code to a REPL or...