Staying at Rene's place was a great decision for my first time in Vienna. His apartment was exactly as advertised- spotlessly clean, relatively central, and comfortable (for up to two people). It wasn't really within walking distance to the city centre, but definitely within biking distance. It was great being able to enjoy the AC during the heat wave. There were no problems with Rene or communicating with him- he is a great guy who was kind enough to let me store my luggage in his apartment for a few hours after I had checked out. I would recommend his apartment for sure!