In the age of UX it is no longer ok to create a beautiful flash site that no one can use. In fact, given the choice, most users will use a not-so-pretty usable site over just a pretty face. I mean look at craigslist. It is about as plain jane as you can get. No “look and feel” to speak of. Which, for me, proves the importance of User Experience (UX). It is more important to pay attention to user needs than have a beautiful website. So, if you have to pick (ideally you can do both), spend time on user research and not as much on brainstorming the look and feel… Because good UX is good design…

“Design is not just what it looks like and feels like. Design is how it works.” Steve Jobs said that.
“Don’t make me think” Steve Krug said that (another smart Steve).

http://www.marsdd.com/mars-library/case-study-craigslist-product-design-with-customers-in-mind