I gave it a shot a couple years ago -- pretty slick. But the latency was noticeable compared to tmux, which I remain using today. I admit that I'm kind of sensitive to it, as at the time I was already on a latent connection.
(Not a dev, just another end user.)
It could also be in my case that I use it so little that some latency is tolerable. I don't develop interactively in zellij or tmux. I mainly keep some logs tailing, and DB consoles open, etc, and I don't check them super often.