The good: the flat is comfortable and cosy. The location is very handy, right next to the subway station. The bedroom is nice, particularly for single travellers, and we didn't have any noise issues. Elisabeth was friendly and helpful, despite some miscommunication.
The not so good: the double bed is not a double mattress, but rather two single mattresses (that are not even the same height). Plus, we needed to assemble the double bed ourselves. Not an onerous task in itself, but it would be nice if the room had been prepared for two guests as per the booking.
As mentioned above, there was some miscommunication re check-in time, however Elisabeth was very helpful in resolving the matter. Unfortunately the check-out situation was a bit more complicated with us being asked to let the next guest in when she arrived, and there being no spare keys available for us to use due to some organisational oversight. In the end it worked out ok, but more due to good luck than good management.