The apartment was perfect for me and my family (one 2-years-old child was travelled with us).
Pros: (1) a lot of space and comfortable beds (2) good location near metro and tram stops (3) very good description and photos, we knew what to expect (4) good instruction and contact with the host (5) a lot of leaflets and informations about attractions in Vienna in apartment as well as book and some crayons for child :)
Cons: none
I'm very glad of choosing that place for our stay.