We really enjoyed our stay in Vienna! Miriam and Philipp's place is beautiful and they keep it wonderfully clean. It is really great for when you want to stay in a place with a kitchen, too- the dishwasher is a huge perk and there is a grocery store within 2 blocks. They also really mean it when they say child friendly! They provided a travel bed, a high chair, and there were lots of toys and books, our little guy loved it! Phillip was very friendly and helpful when getting us settled, and they were always available when we needed them.
The location is in a very nice area with lots of restaurants and shops, and a 15 minute walk to the closest subway (there is also a tram to cut this down but we found we didn't use it often because of the wait and transferring with a stroller). We would say this was the downside, but overall we really liked the place.