*Highly recommended*
Gerhard is a wonderful person and a brilliant host - he helped us to settle in and gave us lots of advice about Vienna and the local area. The apartment was spotless and had everything you could need - it's very bright and spacious - close to public transportation, shops, a lovely park and the canal.
As mentioned in another comment, the apartment is on a main road so can be a little noisy in the evening/night with the windows open but this certainly should not put you off!