Stayed for 2 nights at Maria's place and gotta say I enjoy it! Location is pretty near the main station (15 mins via walk and metro) you can get cheap food along the way as well. it's a quiet street at night and you can get a pretty good sleep.
Didn't meet Maria in person but she's very thoughtful about all the small details, setting up handmade travel guidebooks around Vienna at your fingertips. Vasu, which is Maria's friend, is a great guy as well.
all in all, very very recommended!