Peter was a great host, very quick to respond to questions and his suite is beautiful. The bed and folding couch are both comfortable and the apartment is in an area close to the subway, making it easy to explore Vienna.
The only issues we faced were that the shower door doesn't quite seal all the way, and even if it did, it is prone to leak under the door; I felt like I couldn't take advantage of the beautiful waterfall shower. More importantly, though, we didn't realize the hot water and room heaters couldn't be run simultaneously, or that the central heating unit is touchy and needs to be restarted from time to time. If you keep that in mind as you plan your day, taking into account a few minutes for heating up, you're good to go. Peter is very kind to explain if you have any difficulties!
We really enjoyed our stay and Peter's lovely apartment was integral to our trip.