The situation of the apartment is good. Even it is far on the east, is perctly communicated by public transport, on the U5 underground line that takes you to Alexandreplatz in just 10 minutes.
It is a modern apartment with 3 bathrooms. We were 9 people and there was space for all of us. It has got a complete kitchen and supermarkets near it.
The host let us leave in the afternoon, so we could leave our luggage there during our last day in Berlin.
The only problem we had was that the wifi didn't work very well, but we used it in the underground where it works so good and it's free. Our last day there were some workers in the building and started making noise at 5:45, and we couldn't sleep anymore. This had nothing to do with our host,and was only one day, but was an inconvenience