I didn't meet Ricardo, but his place was superb. It was clean and the room was very bright. I was surprised that, though I had only booked a room, it was like if I had rented the whole apartment, as I was almost the whole time alone! Moreover, though not being right at the city center, the connection to Alexander platz and Prenzlauer Berg are very good, and then you can be there in only 20min.
While being in Berlin, I only met Harold, Ricardo's brother. He was a pretty cool and easy going guy. If you meet him, youĺl certainly have fun.
All in all, I can only strongly recommend this place.