I've been using this for a couple of hours now and, so far, am very happy with it. Performance is fine. (Although I'm on a 1GB RAM Intel iMac, I never had any performance issues with the previous version. I'm managing servers remotely, not playing games...)
As far as multiple connections is concerned, once you have connected, choose File > Save A Connection File and save the equivalent of a bookmark. Do this (once) for each machine to which you wish to connect. Thereafter, simply double-click the connection file in the Finder for each server and you will have multiple connections.
DNS is set up on my machine so that I don't have to enter fully-qualified host names, so the long name issue commented on previously hasn't affected me.
It's a beta, so I'm not going to complain about some rough edges.