No thank you, I prefer Mathematica the way it is for many reasons: 1) New interfaces tend to have bugs and with Wolfram's history of dealing with bugs it might take a couple of versions to fix them all. 2) There might be incompatibility issues with older code. I routinely use code I wrote back in 2005 and it still works. 3) The FrontEnd in Mathematica 8 is *not* archaic but it's just perfect for what's supposed to be, ie a notebook interface. 4) If something ain't broke, don't fix it!
However, now that I think about it, I would indeed like tabs instead of separate windows for my notebooks.