In their work, designers often become expert with the device they are designing. Users are often expert at the task they are trying to perform with t… - Donald Norman

Technologists are not noted for learning from the errors of the past. They look forward, not behind, so they repeat the same problems over and over again. [...] As each new technology matures, customers are no longer happy with the flashy promises of the technology but instead demand understandable and workable designs. Slowly the manufacturers relearn the same basic principles and apply them to their products. The most egregious failures always come from the developers of the most recent technologies.

The major problems facing the development of products that are safer, less prone to error, and easier to use and understand are not technological: they are social and organizational.

Usability is not often thought of as a criterion during the purchasing process. Moreover, unless you actually test a number of units in a realistic environment doing typical tasks, you are not likely to notice the ease or difficulty of use. [...] Do it right there in the store. Do not be afraid to make mistakes or ask stupid questions. Remember, any problems you have are probably the design's fault, not yours.