Unity is a long way from perfect on tablet or PC. Having said that the sidebar has grown on me. Since almost every monitor out there is 16:9; vertical space is precious and another 50 pixels gives me another 2-3 lines of code on the screen.

The best way to use the sidebar is to put your most commonly used program at the top and then launch them with Logo+<Number>.

If you spend some time setting up your shortcut keys you can actually use much of your system mouse free.

So I'm not really sure that it is targeted towards tablets. It could however be adapted to be tablet friendly a lot more easily than the MS Windows interface or older Window managers could be.

So rather than having this jarring difference between Metro and Desktop like you do in Windows 8 they could have a much more subtle transition of the same interface depending on whether a mouse/keyboard was plugged in or not.