We visited Wien during our honeymoon and had a great time! The apt is really cozy and close to the touristic objectives we needed to see.
It is really clean and modern! Dont be scared of the looks of the building, the stairs were not reconditioned for ages, but the apartment is great!
We saw St. Stephan, Albertina, Shonbrunn, Glorriete, Mariahilfen Strasse (10 min walk from the apt), Danube Tower (must see) and Prater today.
The worse thing in Wien is only that eveything is closed so early in the evening (6-7 pm) and Sunday. :)
So, we really recommend Martin's place for your visit in Wien!