Just for the looks really. I wanted to see how far I could go with it, and I was really surprised at how far I was able to go. All the shortcuts you'd expect (Ctrl+tab, Ctrl+shift+t etc), middleclick a link and it opens a new window tab and so on, it's very usable .
There are some issues though, namely: A slight flicker when switching tabs, can't middle click to close a tab (only active) and no middle click to open new a tab (dealbreaker). which is why I'm back to using regular old tabs again now.