The apartment was clean, well equipped, and well-located, about a 20-30 minute walk from a lot of important attractions and less than 10 minutes from the Hauptbahnhof, It is just steps from a good grocery store and subway entrance. Beds were comfortable, bathroom was very nice (good shower). The kitchen was well-equipped and nice.
The most difficult aspect of the stay was communication with the host, who did not seem eager to help or accomodate any specific questions or requests. The number of people changed from three to two during my 9-day stay, and though we knew this from the beginning, he was not willing to adjust the price to reflect that.
The door codes were not very secure (easy to guess -- but also easy to remember!), and the front door of the building did not have a secure lock.
The apartments facing the street have a lot more noise than the apartment facing the courtyard.
Air-conditioning is listed as an amenity, but you must make arrangements for this in advance, and there is an uncharge.
I would stay again, bearing in mind that the host will not be of much help. Despite that, the apartment was still a good value and very good location.