This has to be one of the best rentals in Vienna. It is incredibly easy to reach, both from the airport (CAT + U3, 25 minutes) and from the train station (Westbahnhof, 5 minutes on foot). It has a metro station right in front that takes you straight to the big museums and into the heart of Vienna. There is a supermarket across the street. In other words, within one hour of arriving in Vienna you can stack your fridge and look at a Vermeer painting.
The apartment goes toward a courtyard that is very quiet indeed; you would not know that you are one minute away from one of the busiest shopping districts of Vienna. The ceilings are quite high, which means the rooms are cool in the summer. The apartment has everything you need, including ample space for your wardrobe. There is a balcony with comfortable chairs. The bed, too, is comfortable. There is a large TV and, for European standards, a solid WiFi (it will take some time to download movies, but it's serviceable).
The kitchen has everything you need. There is a funky bath behind the kitchen, and a separate toilet. I was there alone, but I think it's spacious enough for a couple with kids or even two couples.
Thomas is the perfect host; he greeted me to hand over the keys and from then on was never more than 30 mins away from a text or an email.
Why people are still paying for mediocre hotels when they can have something as wonderful as this apartment is beyond me.