Rainer was a very nice guy. During the 3 nights I stayed at his flat, I only saw him on the initial check in. Like the last reviewer states, the apartment is on the 4th floor with no elevator. Rainer was kind enough to carry my very heavy suitcase up all flights of stairs.
The location is excellent, located a short walking distance to the Schwedenplatz and Stephanplatz stops on the U1. Lots of bars and located right below the flat, which created a lot of noise, especially on Friday and Saturday nights. Earplugs helped.
Of note, i believe one or more of the flat mates smokes in the kitchen and the smell of smoke permeates into the room, which is connected to the kitchen. This was a little bit of an issue for me as I am a non-smoker, had a cold, and my cough was worsened due to the smoke.
All in all, a good, affordable place to stay to be in the heart of district 1.