Using 3D virtual environments for educational purposes is becoming attractive because of their rich presentation and interaction capabilities. Furthermore, dynamically adapting the 3D virtual environment to the personal preferences, prior knowledge, skills and competence, learning goals, and the personal or (social) context in which the learning takes place becomes interesting, as there is a bulk of research demonstrating that individualized instruction is superior to the uniform approach of more traditional and one-size-fits-all teaching approaches. However, although such adaptive 3D Virtual Learning Environments (3D VLE) seem to be promising, this needs to be evaluated in practice. Usability of adaptive 3D VLE could be a problem since the user interface could become relatively complex. In this paper, the authors describe an experiment performed to validate the issues of usability and acceptability of an adaptive 3D VLE. This pilot evaluation reveals some important recommendations and improvements.