We stayed in one of the penthouse apartments. The apartment has 2 bedrooms, 2 bathrooms, a large living room, and a large dinning. It also has a kitchen and a washer/dryer. The furnishing is clean and modern. However, that particular apartment does not have air conditioning, while some other apartments in the building do. It was OK for us because we were there during spring time.
You can get to the hotel from the airport by subway costing 4.5 euro. Take S7 (not CRT because it costs 15 euro), change to the U4 train toward Heiligenstadt at Landstrasse station. Get off at the Friedensbrucke station. Once outside the station, go over the bridge. After 2 blocks, you will see the Boro Bakery and the apartment entrance is right next door.
The apartment has a front desk. However, it is only manned a few hours a day. On the day of arrival, the hotel will send you a passkey via email. At the front door, there is a dropbox with a numeric keypad. Enter the passkey, the door key to your apartment will come out. Thus even if you arrive during late hours, you can still get into the apartment. Hotel personnel also live in the apartment. In case of emergency, you may ring that apartment and talk to them via intercom.