We loved our stay at Maureen & Sebastian's! They were so prompt with any message responses and had a thorough little guide to the city which was very helpful! They both spent at least 15 minutes during check in explaining to us what to do and where to go! The flat itself is an easy ride on the O-Tram from the train station and a 10-15 minute Tram Ride to get to the Ring!
They had a fan, which was lovely, as the nights cooled off and we were able to open the upper Windows. You are on the street level, and it is pretty quiet at night, though things start to get busy around 7:00 - If you plan on sleeping later than that, bring some ear plugs along - honestly some ear plugs did the trick just fine for us!
If we're ever back in Vienna, we would definitely stay at Maureen & Sebastian's again!