I bought it last week but I only started playing it yesterday, and as beautiful as it is, it's really surreal. I think I prefer Halo more right now, but we'll see how it goes. I'm currently being shot at a lot by a helicopter.
I did find it hugely fun that I got chased by one of those Civil Protection things after I threw a bottle at him though (this was before they began wanting Freeman's head on a pike).
That man really has no luck with technology whatsoever, does he?