It's the whole package that matters

From Nielsen’s latest Alertbox column:

The websites that had high visual-appeal ratings were then tested for usability. On average, participants’ task-failure rate on these sites was over 50%; this is an unacceptable failure rate based on our tracking of failure rates since 2000. However, despite this atrocious failure rate, participants’ satisfaction ratings remained high. In this case, research indicated that the look and feel of the site had a Halo Effect on the entire site experience, even when these sites were poorly designed for usability.

The easy reading is that visual design can compensate for poor usability. That is too generous. A polished surface does not fix a broken task flow, but it can change how people judge the experience while they are failing their way through it.

This is why treating usability and visual design as separate concerns is so misleading. People do not experience an interface in layers. They experience the whole package, with all the unfairness that implies. Things that look better do not always work better. They are often judged as though they do.