We (4 couples) spent 4 nights in Ralph's appartement. It's perfect for visiting Berlin. The UBahn is very close by. The neighbourhood is nice and quiet. We went twice to the jazz bar 'Yorckschlosschen'. It was brilliant, friendly and great music. (Only round the corner). Also we went to the fantastic Greek restaurant nearby: Taverna Athene.
The flat is very spacious. Unfortunately there's only one bathroom with WC inside. So with 8 people, it can be a bit slow in the morning. But apart from that, it's good value for money.
Ralph was great to communicate with.