Points to note: this is a ground floor (3 steps from road level) flat. The windows are all frosted so it can get a bit claustrophobic. The shower is NOT _in_ the kitchen as others have noted, it is in a separate room Off the kitchen, which is no problem to me anyway. What should be appreciated is that the kitchen is absolutely tiny - just two electric rings, a kettle and a fridge with ice box. No oven, no microwave. This is not really a flat for cooking.
The size of the rooms was great, we found the beds comfortable and there's lots of storage space. The towels were only hand towels which was a bit meagre. The shower was powerful and hot (combi boiler).
The location was convenient for us. I have given the flat a good score because it is a budget price point.
Tip: from the airport you can avoid the premium CAT train €12 pp which goes to Wien Mitte and get a local train instead which does the journey in the same time (although not as frequently) and goes straight to Wien Hauptbahnhof which is about 20 mins walk from the apartment, and only cost us €3.90pp.
Tip2: supermarkets (and pretty much all shops except souvenir shops) close all day on Sunday (and from 6pm on Sat) which was a bit of a shock to us so we had to race around to try to get food for breakfast etc. from one of the few Spar shops that was open. The Aldi/Hofer shop which is the other side of the block was good and cheaper than the Gourmet Spar just over the road from the apartment.