Badass: Making Users Awesome

Sierra argues that people do not care how good a product is, they care how good they are while using it, so the product worth building is the one that makes somebody capable at something they already wanted to be capable at. The book covers the gap between a beginner and an expert, which she calls the valley of suck, and how a product carries somebody across it through better defaults, well chosen practice and the removal of cognitive load that has nothing to do with the skill. The format is unusual, closer to a deck than to prose, and it leans heavily on diagrams. The argument has shaped how a generation of product people think about retention.