The apartment is spacious and in a location where you can we walk into the city centre every day without problem (15mins). The transport network in Vienna is probably one of the best I have ever come across. Uber is super cheap there too (about £5 to the Wien Mitte railway station where you can get the City Airport Train) .
The main part of Vienna (Ringstrassen) is down the hill to the right as you come out the apartment. It is stunning with beautiful buildings everywhere you turn. We were there at Christmas time & I would pre-warn anyone coming at this time of year that from midday on 24th Dec to 27th Dec not a lot is open. Supermarkets, little corner shops, chemists, clothing shops all closed until 27th so you need to be prepared. You will find some restaurants open in the city centre but not many. The Christmas markets & are open right through and are lovely, as are the Christmas lights. We ate in Shebeen pub 2 mins along the road and it was really nice (burgers, curries etc). An ice tray in the freezer of the apartment would've been good but all in all a lovely time was had!