Despite the fact that we never saw Dan, it was easy to communicate with him by phone. The flat is huge, beautiful, not so far from the center (10min by subway, 30min by walk) and near the Schonbrunn palace. We were a group of 16 international students so we were quite noisy and it was complicated to put music and party in the flat after 9-10pm because of the neighbors. So if you are looking for a flat to party with your friends it is probably not the best one. Anyway we really enjoyed our stay and everything was good.
Thank you Dan.