I don't mind it but I hate the implementation. It breaks a few fundamental design rules of osx, draggable area is too small, too difficult to drag a link to the right area of the plus symbol and it just looks plain sloppy. Google has a far better implementation and I can't even stand chrome. Another thing that surprised me is that even though safari is faster, they still have not decreased the memory footprint. Btw where are my iTunes scrollbars!
You can tell they'll do the same thing with the finder when all is said and done. I just hope they perfect the interface by the time snow leopard is released.
The best description so far is on daring fireball. Gruber nailed it right on the head.