Managed to sneak in a short 30 minute stint on Crackdown and I am amazed it is so much better than the excellent demo.  The demo was odd in the fact that it was good, they are normally such poor offering that they nearly put you off playing the full game.

Not even looked at a mission as yet, but this the most freedom I have seen in a free roamer.

One niggle and only a minor one, is that you cannot enter buildings.  But I get that that would have taken to long to achieve