The apartment is bigger than the pictures show with everything you need there for a nice stay.
Having visited Vienna previously I can confirm it is in a great location close to transport links and also close enough to the centre to walk.
The layout is a bit strange and you do have to walk through one bedroom to get to the toilet but this is very manageable. The apartment is quite echoey but that comes with the style of building.
Siegfried offered great communication throughout the process and was there to help as soon as needed.
I would stay again.