Werner's place in Berlin is perfect for great groups such as our family. It's spacious and neat. The bathrooms are huge (something we found hard to get in Europe) and the furniture and appliances are brand new. It's two blocks away from U-bahn and S-bahn stations, so you can get anywhere easily, and a pretty decent low cost supermarket is nearby. We would wake up every day, take a shower and be on the road early in the morning. Late in the evening we would get back to the apartment, get groceries at the supermarket and recover for the next day of exploration.
Werner was also very accessible and friendly (he speaks many languages)!
Highly recommendable.