I’m not a usability expert, but am sensitive to it. I prefer to spend some more time and money on something that works better for the website user, than win some on a quick and dirty solution. It’s important to strive for the goal of creating the perfect fit for the client. The website should be without any frustration, unexpected or unneccesary actions, be as transparent and smooth as possible. This will improve the performance of your website.
The big problem with usability is that is is all so relative. Put some usability experts together and you can have some great discussions.
From a business point of view, we need some objective elements that may help in deciding what to do. Fortunately, a scientific paper , breaking down Usability was written, to help us with a great model giving us more insight on usability.
Basically it says: The ISO organization defines usability as efficiency, effectivity and satisfaction (iso 9241-11). Great, but not very applicable. So the paper drills down and under the first level a second level is created, the usability indicators. They are : learnability, performance speed, errors/safety, memorability and satisfaction and seems to be based on a combination of a definition of nielsen and Schneiderman.
These can be used to classify the means the website uses to improve usability This is the third level of the usability model.
The means are how we may measure the usability of a website: They are consistency, adaptability, task conformance, shortcuts, warning, feedback and undo.
By identifying the means and testing/checking the effectiveness in usability tests, we can make sure the usability is good.
When designing the site, we can use heuristics related to these means, they are the tips mentioned in usability sites.