We stayed (group of 5) for four nights. The place was good, roomy living room, small kitchen but had good facilities and well stocked. The bedrooms and bathrooms were average if not slightly dated but very clean.
The location was ok, in the embassy part of town with a few nice restaurants nearby. It was a 15 mins walk to the center and 5 mins to train station. The only real downside is that there is a construction site right next door which was very loud and started up at around 6.30am! So we always for an early start! Overall a good place to stay whilst in Vienna.