It's certainly pretty. It reminds me of that quote by Joel Spolsky - "people ridiculously overvalue aesthetics and beauty when evaluating products. It's one of the reasons iPods, and, for that matter, Keanu Reeves, are so successful."

I don't think usability-wise it's all that great though. If you have multiple chatrooms in multiple slack organizations, it's a PITA checking on them all, for instance.