Klaus' place is very comfortable and in a good location but we had difficulty with our check in. We are currently on a 3 month holiday and so have a fair bit of luggage with us. We also had an early flight and so we arrived at the airport at 8am. I understand check in times are often around 2pm but we were given a check in window of 6pm-6.30pm which meant we had to find somewhere to store our luggage. Not an easy task at the very busy Alexanderplatz station. If you are travelling light this issue won't affect you. Just a warning for long distance or long term travellers. Other than this minor issue, Klaus was friendly and the room was spacious and comfortable.