Martin was the perfect host. He waited for us in the street, showed us around the apartment, left us some food in the fridge, he even gave us the opportunity to stay a bit longer. The apartment itself is simply gorgeous: very nice interior, very good connection to tram and metro. The building itself is being renovated, but this is only a minor nuisance, and for guests arriving after winter 2015, not even that (I guess it will be completed by then).
My only complaint was in connection with the bathroom. It's small. I mean small as humanly possible. Any smaller, and it borders on being unusable. (I'm 190 cm and 83 kgs, so YMMV.)
But this is only a minor complaint, and I can recommend the apartment wholeheartedly.