I had a fine stay at Siu's place when visiting Vienna and Klosterneuburg for work. The location is easy to reach by bus or by foot from Heiligenstadt Station, and from there you have good connections to the rest of Vienna.
The room is big, with plenty of space to relax on the sofa or work at the table.
There is a big road outside which can be a bit noisy in the daytime. It was not a problem for me to fall asleep. The kitchen and bathroom are shared with the other flatmates. During the week I only saw them a few times. The place did not seem crowded and the flatmates were nice and friendly. I would recommend Siu's place - it is good value for money.