I don't understand how curved tabs are supposed to get "out of the way". The new design seems to use less standard UI elements to push it's own (WinXP / Fisher-Price) agenda: I don't see any gains here and I reckon they just want to appeal to the chrome crowd.

And I can't fathom why you'd focus in on curved tabs in this UI redesign. It's one of the smallest details.

Which is the big one then?

The removal of most UI customization.

I really wish browsers were like emacs and that one could replace the whole UI on a dull rainy day.

uh, with firefox you pretty much can.

Try removing the button on the top left. The one with the three horizontal bars.