I probably know about 5% of tmux, but I freaking love it. I've had a tmux session with 12 sub-windows running on a server for 300 days. I connect to it daily, from different machines. It works. It does everything.

I have no desktop application that performs at this level. So my hat's off to the tmux developers. Like many other great open source tools, it's a critical part of my toolset.