I think his declaring something as impressive or not in an objective way is fraught with peril since impression is always a subjective feeling. If it impressed

I think his declaring something as impressive or not in an objective way is fraught with peril since impression is always a subjective feeling. If it impressed you, it is impressive. However that being said 2.days.ago is not a particularly differentiating bit of magic because as has been stated elsewhere every object oriented language that allows extensions of primitive types will allow this. The main question here though is whether 2.days.ago is a good design and does it really demonstrate expressiveness, which as has also been stated above related more to the concept of "small pieces, loosely joined" 2.days.ago breaks encapsulation and abstraction and inverts the flow of control (parameter calls function).