Aside from technical R&D and outreach activities in the Aniketos project, one part of the project work comprised of validation and end user evaluation tasks. We describe the particular characteristics of the Aniketos project evaluation and the overall challenges we encountered during our evaluation tasks. These challenges are structured along four elements of evaluation work; viz., 1) project-internal stakeholders who were doing evaluation work or benefiting from the findings, 2) the developed objects that were evaluated, 3) the development process in which the evaluation process was embedded, and 4) the beneficiaries of the project outcome who participated in evaluation studies. We outline the multi-perspective evaluation approach pursued to address these challenges and to ultimately conduct evaluations of such a highly complex and multifaceted project. We conclude with examples and lessons learned from our evaluation work and provide recommendations for project evaluations under similar conditions.