My main complain about tmux is that it messes with my terminal emulator scroll buffer. I like to use a mouse to scroll my terminal emulator. For example I can do `cat file` and then scroll around. If file is huge, `less` is better, of course, but for most things terminal scrolling is perfect. But `tmux` and `screen` completely ruin that experience. I know that they have their own scrollbuffer and scroll mode and all that, but I've found that perfect user experience for me is to blend GUI approach and text mode approach instead of replacing it.