We just spent 5 nights at Manfreds apt, and it was wonderful. The location is ideal, right across the street from Hunderwasserhaus, so the view is also excellent. The apartment is huge, with a massive couch ideal for resting after walking around Vienna all day. The bedrooms are situated nicely for privacy, as there is one off the living room with a bathroom/shower, and two down the hall near the front entrance with a second bathroom/shower, giving it the feel of its own 'wing' in the residence.
We will definitely be back!