Judging by the screenshots it does look quite similar, nice. Do you know whether it works well on mobile? That's one of the main selling points for many users. The tmux+ssh user experience is not that great on mobile :)
Well, for quassel, there's also a mobile app. On the Play Store the beta version is quite neat, and the F-Droid version. The normal Play Store version is from 2013, though.
I - maintainer of QuasselDroid - am currently working on a next version, though, which will take another few months.
For iOS, though, quassel-webserver is the best you'll be able to get, and it's quite meh on mobile.
