The place is conveniently located, close to U/S station. It matches perfectly the picture. For us the stairs were not a problem, as we did not need to climb them a lot. A slight inconvenient might be the temperature in the apartment, as it was a bit colder than we are used to. But we spent the majority of time outside the apartment, so this was not an issue for us.
Rainer is a great host, very responsive. He provided us clear indications on how to arrive to the place. Also, we could leave our luggage in the flat slightly more than the check-out time.
I would definitely recommend the place.