During our stay in Berlin, we stayed in Helens room, and it was really great. Everything was well prepared, and the room itself was very cosy and welcoming. The bed is absolutely comfortable, so we slept more than just good. Also the rest of the apartment is quite comfortable, and we also could have used the kitchen-stuff if we wanted to.
She and her roommates are very kind and helpful. Unfortunately Helen spend the weekend herself abroad, so we couldn't talk that much with her. But she was reachable and we had her number, in case we had any questions.
An extra plus is the location, which is only a few minutes from the U-Bahn, and actually in the centre of an area full of bars and options to go out.
We will absolutely book the room again, if we'll be going to Berlin again, and I recommend it to everyone! :)