This is my second time staying in Andrei's guest rooms and the first time in the Grey apartment. The space is very roomy and well decorated; it closely matches the description on the profile site.
The only drawback is that the apartment is starting to show some signs of wear and tear (especially the flooring, but also some missing glassware probably broken by others, exposed wiring from a light fixture, etc). It also has a GREAT deal of natural light-- which is wonderful at all times of day, except for early morning!
All in all, a lovely place to spend a few days (or more) in central Vienna.