Best third person gunfights in a game ever, and it doesn't even have to resort to dual-wielding weapons or slow-mo. I love the small discrete effects, like the fatally wounded attempting to creep away on the floor, or how your shots can actually penetrate through some materials like thin wooden frames, doors, cars or furniture. The best comparison I have is the sublime end gunfight in L.A. Confidential with Guy Pearce and Russel Crowe holed up in the motel.
Lovely Django Reihardt music, of whom I was a fan even before playing the game, yet it fits perfectly. Minor Swing crackling from the radio while purring around in a Duesenberg J in Little Italy is perfect.
I love vintage cars (Luuuurved the race and roaring through the city in a Bugatti), art-déco architecture, Chicago and New York, prohibition era Americana, and mob movies. It's like it was tailor-made for me. Possibly my favourite game ever.
If it breaks, you get to keep both pieces.