With the increasing application of web services in our lives, selecting the right web service is becoming unprecedentedly difficult. Indeed, before paying the price of a web service, the customer always tries to make sure of his choice. One of the mechanisms used to put the customer in trust is to make available the opinions of other customers who have already used this web service. In the literature, many solutions for measuring the reputation of web services have been proposed. Unfortunately, they ignore certain aspects that we find important to ensure a more meaningful assessment of the reputation. Firstly, consumers do not always have the same satisfaction criteria, and as a result, they can judge the same web service differently. Thus, without knowing the consumer's preferences, it is almost impossible to give meaning to his opinion. Secondly, the qualities of a web service can be changed over time, and hence, the old ratings are no longer representative. In this chapter, the authors propose a novel reputation computation approach to deal with the problems mentioned above.