We had a great stay at Peter's apartment. We flew in on a Friday afternoon from the US and took a cab from the airport per Peter's recommendation which was about 40 euro. The location was ideal for us: a 15 minute walk from the opera house and entrance to inner city, enough away so that it was quiet and got us a few streets out to feel like real Viennese and not tourists.
The apartment is in a beautiful old building but modern and clean with a nice and comfortable bed. It's the perfect size for a couple. The kitchen is actually big enough to cook in but we didn't. The apartment is also one street over from the outdoor market which is very convenient. We also had fun one night at the bar down the street, Einhorn, but be prepared to wash your clothes after since everyone smokes inside.
All around great stay and Peter was very helpful and thorough with directions!