From what I can figure it is actively calling itself a multiplexer, so pretty closely linked to something like tmux (one of the review videos on the page calls it a "tmux rewrite").
But they seem to be targeting very different scopes use wise.
I think if you use this to do stuff like, edit files, run htop, drop into an interactive shell, compile some code, my guess is you're gonna be fighting uphill and have a bad time.
On the other hand, if you're only using tmux so that you can have a bunch of terminal windows for agents. Then this is probably going to make your workflow a fair bit smoother.
What? Do y'all even try it before saying things like this?
I use it primarily as a replacement for tmux to do terminal stuff, not use agents. It's awesome. It worked out of the box, has actually good, working mouse support, quickly ships fixes, and the defaults are sane with obvious behaviors represented in an intuitive TUI.