Arne is a really fantastic host, the communication with him was really precise and he's very reactive. We had a very warm welcome, he really cares about his guests. We had some trouble at the end of the trip to get back home and Arne was always ready to help.
We stayed in a comfortable room with a little bed (for 2 people) but sufficient, there was places to tidy our stuffs. The insulation of the appartment is not perfect but it's calm. The decoration is nice and the balcony very peaceful.
Mitte is an amazing district where you can find all you need, so much restaurants, galleries, stores, parks,... and also very close of the transports.
We just have to say that Arne has 2 cats, cute and sweet but also very curious, so it may be annoying for some people.
Anyway, we absolute recommand Arne's place.