Everything went fine with Petra: good communication, perfect planning, she was kind enough to help us take our luggage through the stairs. She also arranged us to let our luggage in the room the last day and pick them later in the afternoon before our flight.
The apartment is really nice, cosy, with all the equipements you need. Ideally located, close to bus, metro and tramway station. There is also a shopping mall very close and a lot of bars and restaurants. All tourist zones are at walking distance (10 to 20mnt walk).
The roof in some corners may however be quite low which may not be very confortable if you're an average sized person. You may find yourself bending a lot. Also the access to the upper room is not that easy so you may want to choose which person takes this room depending on how tall/corpulent you and your friends are.
Nothing however keeping me from going there again, we had a great stay at Petra's place and I totally recommend this apartment.