Lots of great tips about how to build your engineering process around your users, from soup to nuts. Hiring an outside design team to design your UI - what a concept! :)
Here is just one tip to whet your appetite:
UI tip #6: Let user demand defend against code creep.
" Our team strove to understand what is necessary versus what's desirable," Ries says. "Everything you add in to the product affects documentation, support, and code.
"With every feature, you have to make a design decision. We tried to make reasonable and good assumptions about setting limits; we actively eliminated options, and then validated those options with the users.
"We ran into lots of feature that are good ideas, but they were clipped until we can get enough evidence that there's enough demand. There are always next versions that we can use to include them."