The place is really well located, in a nice neighbourhood and very close to the metro and well connected by bus as well.
The bedroom was massive (though the bed was a bit noisy) and the whole house was very nicely decorated and spacious. The bathroom is also very big and the rain shower is great!
We just had some minor issues at check-in, after exchanging some messages, as we were already on our way with all our luggage when Chris told us he had to leave so we had to wait in a cafe nearby (though he promptly offered to pay for the cafe expenses).
The flat is located in a first floor with no elevator, which was a bit of a pain, as we didn't know and we were carrying a lot of luggage and I have a back problem. However Chris helped with one of the suitcases on the way up (thanks Chris!).
Apart from the two lovely cats there was also a newborn in the house, which we only found out on day 2. It immediately made us be very self aware of any noise we could make to disturb him and the new parents. The baby himself didn't cry loud a lot, so we weren't bothered by this during our sleep at all.
I would recommend this flat for a Berlin holiday, overall we had a nice stay and Chris and his gf were very friendly.