I loved the loft. Andrei is an excellent host. Margareten is a very interesting and nice neighborhood. Naschmarkt is a 5 minute walk. There are many good restaurants at the market (e.g., Cafe Neni) and elsewhere in the neighborhood (restaurant Finkh has great Austrian food). Uber will take you anywhere in Vienna for pennies (I never paid more than 8 Euros).
I did not mind climbing four stories although that may be a challenge for some people. Because this is a loft, the place can get very hot in the summer, but ventilation is good and a fan is provided. The problem is only when it is both hot and raining and you cannot open the windows that are on the roof of the bedroom.
In sum, I recommend the place highly.