My friend and I stayed for two nights at Sigrid's apartment. It's about 2 minutes walk from metro station (U1) and it takes about 5-7 minutes to get to the center, which is really good. There are indeed a lot of little shops that work even on Sundays (which is rare for Vienna, keep that in mind), where you can buy some snacks, and cafes. Even a supermarket is nearby. So, if you have Vienna 48h ticket for public transport like we did, the location is great.
Apartment is great as well. Everything is clean and pretty, the bed is comfortable, you'll find everything you might need in your room: an electric kettle, a toaster, a blowdryer, cups and plates. The only thing was that the mini refrigerator under the table wasn't working but we talked to Sigrid and she let us put our food in her refrigerator, so it wasn't a problem after all. (The kitchen was a private space btw).
And the breakfast! It was one of the best moments in Vienna for us! We didn't expect it to be so good! Sigrid asked us beforehand when we would like to have our breakfast and what we like to drink in the morning - tea or coffee. And there was a plate full of different fruits that was available to us all the time.
One of the best stays. Totally recommend!