This is an absolutely delightful apartment, located in a lovely neighbourhood that is very accessible to all the important sites in Vienna. Pilgramgasse subway is a very easy walk and you can get from there to anywhere. Yes, you must climb steps to the fourth floor, so not so good if you have lots of luggage (or a heart condition), but, for me, it was definitely worth the effort. The apartment is so well designed, decorated so beautifully and is impeccably clean. I loved it and would happily return, ideally for a week or more. Andrei is a great host too.
Highly recommended.