I totally recommend the room in Tanja's appartment. The room is big and there is plenty of closet space so no need to live out your backpack. It's a clean room, just as the rest of the house is. Tanja is a really nice an friendly person. We always had a nice chat when we saw each other in the house, but I also felt free to take my own space. Tanja was always willing to help me out when necessary.
The location of the room is really good. At the end of the street there are two small grocery stores. The street has some nice cafe's and restaurants. Furthermore there are a lot plublic transport options to take in the street or around the corner that will bring you through the whole city. And with a 20 minutes train ride you can be at a really nice lake just outside Berlin.