This apartment is fantastic - you really do not need to consider anywhere else in central Vienna. Very well located in an upmarket and quiet apartment block, close to major sights of interest and public transport nodes.
Good space, faultlessly clean, luxurious but practical and comfortable design, well equipped with everything you could need (and more), with lots of very thoughtful touches that show Simon and his colleagues also care about the little things and the experience of their guests. From communication beforehand and during our stay, to going above and beyond to arrange for late check-in, to the little welcome packages in the apartment on our arrival, it was all A++. Can recommend very highly!