Newbie puzzled by H-Bridge

Nick, your arrows are pointing towards you pnp transistors, I think they should be pointing away from them as you sink the base on the pnp's not drive them but you've explained it well,
Here is a circuit i like, it uses a small npn to sink the pnp base and drive the npn base at the same time requiring only switching between forward and reverse, I have tried and tested this circuit and it works well