From start to finish, staying at Jan's was a pleasure! He uses it for an office space when not renting it out for travelers, but it has everything you need for a comfy stay. My husband and I were here for 3 nights in December 2015.
Jan met us on the first night upon our check in. He was friendly and talkative and gave many great suggestions, even drawing us a map and answering our questions about the history of the space (it used to be a lawyer's office, then was used to store washing and drying machines before Jan turned it into his architecture office).
The heat worked well, the shower pressure was as expected, and the room itself was nice because it was separated from the rest of the open office area. I did get a little chilly at night (but that happens in my own home), but I kept my socks and a light sweater on before going to bed and that did the trick. We found the location to be convenient to reach the airport and the downtown areas through the tram stops and the metro station nearby.
Jan even let us keep our luggage in a separate locked storage room after check out. He gave us a different key for that and we came back to pick up our luggage right before going to the airport. It made it so easy to enjoy our last day in Vienna to not have to carry our suitcases with us.
I would definitely recommend renting Jan's unique listing!