Is there anything in Revelations that would lead you to recommend it over Brotherhood, for instance? I honestly can't think of anything. There were some optional features that felt relatively harmless (grenades, Desmond's Tron missions, ziplines), but the only thing it really has going for it is the new city. And when it comes down to a sense of place, I think Rome and even Venice from AC2 were far better realized. I guess I liked that guards would occasionally fight each other, and I don't think there's anything like that in the previous games. But otherwise, I'd rather just play Brotherhood some more.