Very supportive working environment and highly interdisciplinary working groups. The conditions are very good and I do not think such good conditions can be found somewhere else. Also trainees are allowed to join coursed and the best is, it is free for the trainees. Sometime it is possible to join external conferences and meetings (strongly depending on the group/ department)
Cons
Graduate trainees (even when they have already a PhD. or work experience in industry) are not considered as employee and therefore are not allowed to do any work which comes with a certain responsibility. So the work themselves can be often very low challenging.