My boyfriend and I spent a month at Hannes's place, and we had a very good experience. The apartment looks identical to the photos. There were no surprises. Check-in was easy and efficient. Hannes met us outside and spent almost an hour showing us around and answering our questions. He checked in with us over text and very kindly brought us two fans toward the end of our stay when it was getting warmer. (The unit has no A/C, as is common in Europe.)
Over the course of the month, we used all the appliances in the apartment (stove, oven, microwave, kettle, Nespresso machine, dishwasher, washing machine), all of which work just fine. There was sufficient supply of all dishes and kitchenware for us to cook regularly for ourselves. Hannes also supplied spices (salt, pepper, oregano, and a couple others) and olive oil. The pantry was stocked with some other items too (flour, etc). We used some of the provided coffee pods but also purchased our own - you just need to buy Nespresso compatible pods.
It would genuinely be hard to beat the location. Marxergasse is a fairly quiet street, and Hannes's apartment, as you can tell from the photos, is in the back, overlooking a park. There was very little noise. There are both tram and bus stops within a 2-minute walk, an U-Bahn line within an 8-minute walk, and another U-Bahn line and various S-Bahn lines (at Wien Mitte) within a 12-minute walk. In other words, you can get to the 1st district very easily (still only 10-15 minutes on foot) but you're not among the throngs of tourists there. While we stayed for a month, we could also imagine this being a great spot for someone who is spending only a few in Vienna but wants to stay in a place that feels more neighborhood-y.
The biggest downside for us is unaddressable, but cigarette smoke regularly comes into the apartment. Residents in the other units overhanging the park regularly smoked at night, so it especially filtered in when we had the windows open in the evenings. Even with the windows closed (which wasn't often the case for us), it somehow came through the vents in the bathroom.
Our recommendations on local food and cafes:
Cafe Zartl (beautiful corner building at the intersection with Löwengasse) - good for the experience of an old-world Viennese cafe (upholstered booths, etc.), not so great for the coffee. Cash only.
Cafe Mente (Radetskyplatz) - better coffee, modern ambience, we found it an effective work spot.
Grocery stores - abundant. Our favorite was the Billa Plus in Rochusmarkt, but the Hofer (Austrian rebrand of Aldi) across the street works for a few small things. Note: grocery stores in Austria are closed Sundays.
Bakeries - also abundant. We most often went to the Ströck near the Hundertwasserhaus. The Josefbrot on the Landstrasser Hauptstrasse was also worth the stop.