Joel Spolsky - Talk at Yale: Part 1 of 3:
"The old testers at Microsoft checked lots of things: they checked if fonts were consistent and legible, they checked that the location of controls on dialog boxes was reasonable and neatly aligned, they checked whether the screen flickered when you did things, they looked at how the UI flowed, they considered how easy the software was to use, how consistent the wording was, they worried about performance, they checked the spelling and grammar of all the error messages, and they spent a lot of time making sure that the user interface was consistent from one part of the product to another, because a consistent user interface is easier to use than an inconsistent one.
None of those things could be checked by automated scripts. And so one result of the new emphasis on automated testing was that the Vista release of Windows was extremely inconsistent and unpolished. Lots of obvious problems got through in the final product… none of which was a “bug” by the definition of the automated scripts, but every one of which contributed to the general feeling that Vista was a downgrade from XP."