Getting the details right is the difference between something that delights, and something customers tolerate.
Your software, your product, is nothing more than a collection of tiny details. If you don’t obsess over all those details, if you think it’s OK to concentrate on the “important” parts and continue to ignore the other umpteen dozen tiny little ways your product annoys the people who use it on a daily basis – you’re not creating great software. Someone else is. I hope for your sake they aren’t your competitor.
This Is All Your App Is: a Collection of Tiny Details
Jeff Atwood, Coding Horror, May 7, 2012