In general, subjective satisfaction ratings are not a very telling usability measure because users tend give generous scores even when they have great difficulty using a design. One reason for this is the general human desire to be polite and fit in. Another reason is that users often don't know how poorly they performed when they tested a site. If they found some information about their problem, they think that the site was helpfulthey don't realize that it may have had a great deal more relevant information that it did not make readily available to them.
On a 1-to-7 scale in which 7 is the most satisfactory experience, the average score our users gave the 25 sites we tested was 4.7. In analyzing the usability of a user interface, we rarely analyze these scores except to note if there's something that people particularly like or despise about a site. However, the fact that satisfaction ratings for our study were reasonable indicates that we had picked a representative sample of current Web designs that pretty much matched users' prior expectations as to the current state of usability.