Well, I did start from scratch and just finished the game on the iPad. Great game to begin with - and surprisingly even better on the iPad compared to the iPhone (the bigger screen goes a long way in improving the controls).
Anyway, I wish Telltale make this into a proper season. It is really this good. (Although, seeing how they are already giving it away for free with BTTF, I fear the game didn't really sell all this well now did it?)