This is a very good location.
If you catch the S7 from the airport which is a ticket of just €2:60 then in 25 minutes you are in a station called Vienna Mitte that is just 15 minutes walk from the apartment.
The number 1 tram, which forms part of the ring system that circles the old town, runs past the corner of the street and it goes straight to the Opera House.
Across the bridge is a small tobacco shop from where you can then buy a 24 hour ticket for €8 and this allows you to use all the trams, buses, metros etc in Vienna.