Agile development methodologies have gained great interest in research and practice. As their introduction considerably changes traditional working habits of developers, the long-term acceptance of agile methodologies becomes a critical success factor. Yet, current studies primarily examine the early adoption stage of agile methodologies. To investigate the long-term acceptance, we conducted a study at a leading insurance company that introduced Scrum in 2007. Using a qualitative research design and the Diffusion of Innovations Theory as a lens for analysis, we gained in-depth insights into factors influencing the acceptance of Scrum. Particularly, developers felt Scrum to be more compatible to their actual working practices. Moreover, they perceived the use of Scrum to deliver numerous relative advantages. However, we also identified possible barriers to acceptance since developers felt both the complexity of Scrum and the required discipline to be higher in comparison with traditional development methodologies.