What I don't like is that Windows is forcing users into a specific interface paradigm. In the Linux world, most distributions offer a wide variety of desktop paradigms, so when Ubuntu wanted to switch to Unity, users were just a couple of clicks away from logging into Ubuntu Classic (Gnome2), or if they don't like any of the ones that come pre-installed, they can easily install others. That way, you can have one computer with a "traditional" interface (Gnome2, qvwm...), an innovative interface (Gnome3, Unity...), and different types that just never got mainstream attention (xmonad, Awesome ...)

Besides giving users choice and creating competition, this allows people to experiment and inovate with new systems with much less risk than Windows model of forcing people to use their latest and hoping for the best.