Got this game in the mail yesterday, and so far it is just as good as the demo.
The most difficult thing i've found so far though is actually finding the wine bottles (which you're supposed to shoot) and stolen gold bars.
Edit: So far, the hardest 'boss' is Hitler in the 'Assassinating The Fuhrer' DLC that came with my copy of the game. The coward is fast on his feet, and keeps getting to cover (or the train that lets him escape) before i can shoot him.
Edit2: I do wonder where i can find the longest distance to shoot an enemy at...