Mobility as a Service (MaaS) is an innovative urban mobility concept that aims to provide a competitive alternative to the use of private cars, by integrating various transportation services. Until today, limited MaaS schemes have been implemented and, in most cases, without succeeding to justify the hype. For achieving the goals of MaaS it is essential to capture holistically the expectations and barriers, as perceived by both the end-users and the various involved stakeholders. This paper aims to bridge this gap, by conducting two surveys in the city of Thessaloniki, Greece; the first survey targeted local authorities, organizations and mobility providers, while the second survey focused on (potential) end-users. The responses of stakeholders were analyzed through the Analytic Hierarchy Process (AHP) method, in order to identify the importance of barriers and expectations. On the other hand, the responses of end-users were analyzed statistically and two ordered logit models were developed for identifying the characteristics of those that are more likely to adopt MaaS. The results of the analyses indicate that there is a loop between MaaS and private car usage; on the one hand, the dominance of private cars hinders the adoption of MaaS, but on the other hand, MaaS can be a “tool” for encountering car domination. The results also enhance the idea that public transport is an essential component of MaaS.