For our group of 10 colleagues this apartment was a good pick. With all the extra beds added in, there was a separate bed for every one of us. Some of the extra beds were a bit short, so take that into account when deciding who sleeps where.
There are two living rooms, by carefully moving a table and some chairs from one to the other you can turn one of these into a room where you can eat together with your entire group. Also plenty of bathrooms with good showers.
Communication with the host was enjoyable.
The location is great, a pretty quiet street from which you can easily explore Berlin. At walking distance from Ostbahnhof. Be sure to visit Markthalle Neun nearby.