There is no need to install Mint when you can have Mint GNOME Shell
Extensions in Ubuntu, unless you specifically want Mint or Mate. I
think there is a typo in the last line of the cut and paste sudo
commands. I think that it is gnome-tweak-tool and not gnome-tweak.

www.howtoforge.com/install-gnome-3-with-mint-gnome-shell-extensions-or-ma\
te-on-ubuntu-11.10-oneiric-ocelot