Michael's place has probably the best location of any apartment we've stayed in. The airport bus drops off about a 2 minute walk away, it's another 2 minutes to trams and subways, and about a 15 second walk (literally) from the main shopping drag. There's a supermarket a minute walk away as well, which we used extensively. And, for American's missing home, there's a McDonald's a block away. If you're sightseeing Vienna, this location can't possibly be beat. I can't emphasize that enough.
The accommodation is nice, exceptionally clean, modern, and a little spartan. It's not small but it's not spacious either. Lack of AC in Vienna shouldn't be an issue, but we were there in a heat wave and it was uncomfortable at night for those of us who like it cold. He provided two very powerful fans that made a big difference. The major high point was the comfort of the bed, which was very soft.
Michael is running a professional if impersonal operation. We never met him in person, but his colleagues let us in. Not a lot of introduction or recommendations; communication was sufficient.
In the end, you can't possibly beat the location at this price. I would stay here again in a heartbeat.