Nowadays, Peer-to-Peer (P2P) architectures are becoming more popular in content delivery applications thanks to their valuable characteristics as scalability, performance and low maintenance costs. In those systems, peers share their resources automatically (bandwidth, storage, etc.) and not only download content but also upload content to other peers organized in a neighbourhood. Each peer' neighbourhood is based basically on QoS-related parameters (available bandwidth, number of connections, etc.) and the amount of exchanged content. We consider that peers are under control of users that are autonomous and free persons having rights, preferences and interests. As users' resources are the richness of P2P systems, we think it is important to satisfy their preferences beyond the QoS. In this paper we present first experimental results of WUW (What Users Want), a service located on top of a P2P layer and proposed to satisfy users' preferences during content exchange. In the current implementation we use the BitTorrent protocol for measuring to which extent users' preferences influence the P2P behaviour when WUW is used. We describe how the experimental scenarios are built using the resources provided by Grid'5000. Our preliminary results are encouraging because they show a low overhead of WUW on the global content sharing performance.