I'm using it on a laptop under Ubuntu. It's nifty, but I've seen similar functionality in Opera via plugins. And I'm not a huge social networker, so maybe some of it is lost on me.
As far as I can tell, it is Firefox with a few features added in... I do not see anything all that special about it. Granted, they are some nice features, but they could have just as easily made them add-ons for Firefox.