The Smart Energy Community topic has attracted a lot of interest from policy, research centres, companies and private citizens since 2018, when in Europe the recast of the Renewable Energy Directive, and later in 2019 the Internal Electricity Market Directive, came into force to support the new role of users in energy systems. Following these directives, energy community experimentations, real projects and/or simulations and case studies have been developed and investigated in the literature. In this review paper, an investigation of recent literature about Smart Energy Communities in terms of common characteristics, fundamental scopes, and principal indexes used for their evaluation, has been realized by considering 111 scientific references, 78 of which have been published since 2018. The reference papers have been selected through the “Preferred Reporting Items for Systematic reviews and Meta-Analysis” methodology. In developing the review, significant barriers to Smart Energy Communities’ diffusion emerged. The main shortcomings concern citizens’ uncertainty about these new projects, due to their poor information and technical skills. These issues often hide energy, economic, environmental, and social benefits of Smart Energy Communities. Therefore, this study wants to be an opportunity for bringing to the attention of citizens Smart Energy Communities’ positive outcomes, especially from the social point of view, thus boosting their spreading and overcoming still existing criticalities.