"A framework to simulate how customers experience your product, especially the moments of confusion." - Brian Armstrong
On the "books read" section of Ev Williams' GoodReads profile.
"The single best book on usability I've ever read." - Jeff Atwood
"About usability and making software and user interfaces that are friendly to people." - Nick Ganju
"The simplest book I recommend everyone to read when they want to do design." - Garry Tan