Some people assume that Scrum's approach to planning lacks documentation. They assume that the lack of a massive functional spec document means you're making things up as you go along. That's wrong, obviously. User stories are awesome, but they're not the end of the process.
A few months ago I did (along with the other partners at Fudge) a talk at Northern Digitals about a project that went wrong. It was the worst six months of work we'd ever been through. Sounds dramatic, but it's true.
As far as I'm concerned, most of the problems we encountered were caused by the 200 page functional spec that we laboured over for months. As far as we knew, the client understood and agreed to everything we proposed to build. We had a signature after all. We were very wrong.
The project that went wrong made me re-think our approach to project management, design and build. Everything really. The biggest impact from my perspective came from the adoption of the empirical approach to planning that Scrum provides.
