We had a fantastic stay in Andrei's place. We arrived slightly late in the day, but had no problems getting to and into our loft thanks to the very detailed instructions provided.
Andrei's place was very clean, warm (in Winter) and provided everything we needed.
The street and building is full of character and quintessentially Viennese, but usefully also near a trendy cosmopolitan area. The Metro is just round the corner, but we ended up walking around the city as everything was so close (most days via the Naschmarkt for a cheap, tasty breakfast).
Definitely stay here if you are going to Vienna.
Thanks Andrei for having us, we really enjoyed our stay.