I found the location of the apartment to be perfect. It is very close to the main train station (where the CAT train arrives from the airport only taking 16 minutes) and an easy walk into first district and all the sights. The apartment was a good size, clean (apart from a few hairs found in the shower) but a little dated. Harry was not the most responsive of hosts but became more responsive an hour before I arrived which made check-in awkward. Vienna however is a BEAUTIFUL city! Also a tip; there is free luggage storage (large bags fit too!) at the Landstraße Station in the CAT office.