I assume by the "back button" you are referring to the text saying "Voke" on each page?
I wouldn't have clicked it until looking for a back button. Might be worth leaving it as text, and maybe placing a back button to the left of it? Personally I think something similar to the back button in Windows Phone would look nice.
Something like the button here: http://i.msdn.microsoft.com/dynimg/IC505392.png
I was referring to just the standard browser back button, ha. I'm using the HTML5 history API for this, and the back button was causing recursion problems. That said, I know what you mean, and that could be a good idea.
I wouldn't have clicked it until looking for a back button. Might be worth leaving it as text, and maybe placing a back button to the left of it? Personally I think something similar to the back button in Windows Phone would look nice. Something like the button here: http://i.msdn.microsoft.com/dynimg/IC505392.png