I am going to add my praise to all the other reviews that Jafar has already received.
I was a solo traveler. The apartment had everything I needed for my stay and when I say that the location was great I'm not exaggerating. The nearest underground stop is less than a 5 min walk as is a Eurospar. There are restaurants, coffee shops very close by too.
Many of the attractions I wanted to see were even within walking distance with no need for transport at all.
If you get a chance to book Jafars apartment then book it as it will be the best decision besides the decision to go to Vienna in the first place!