I seem to be in a minority but I find user stories or features to be really awkward and unnatural units of work for building software. Sure these things help to define the expected result but they shouldn't directly drive the development process. Imagine building a house that way - you don't build the living room, then the kitchen, then the bathroom etc.; you build floors, walls, the roof... The 'features' or use cases for the building arise out of the combination of different elements that were put into it, and usually right near the end of the build. The same is true for basically anything else that we build or create - if you're making a sculpture, do you finish working on one leg first before you move onto some other part?
Features are vertical slices through the software cake, but the cake is actually made out of horizontal layers. Creating a bunch of servings of cake and then trying to stick them together just results in a fragile mess that's difficult to work with and easy to break.
replies(9):