An excellent film...! It presented some really interesting moral dilemmas and the downhill spiral that The Joker's philosophy presented was intense. Half way through I thought 'but this isn't as good as the first one', but in the end I think I shall have to think again...
And of course, the unstoppable force, immoveable object question as posed by the joker is also posed in the Iain Banks novel Walking on Glass which is a very fine book. I'm not sure I really understood what was going on in the end, but sometimes that isn't always necessary: it is enjoying what is going on whilst you get there...