Ubuntu on Linux gives you a decent commandline, not a whole lot more. Still some questions on upgrades etc ("apt-get update && apt-get upgrade" typically fails badly). What about Linux software with GUIs, or ports of such? Homebrew so far beats the stuff for Windows by a far margin. You get timely upgrades, and it can be used to install, run and upgrade most of the ported Linux GUI apps as well. Having said that, Ubuntu on Windows looks like a great start! With some decent package management it could be very cool.