It's better than tmux. I've used both extensively, there's no reason to use tmux again.
You end up having to wrap everything in adapter scripts because it is so verbose as well as so unmemorable, along with that, it has no built in help, not even -h
I never heard of this project but in 5 minutes I got the features that I wanted without having to introduce muscle memory. I just wanted a dead simple way to point and click to select different terminals. The only thing I neeed to remember now is "ctrl-b + v" to create a new pane.