This is a great place! With the huge windows and high ceilings, the apartment gets so much natural light, even on cloudy days, and has a very spacious feel. The decor is stylish, bed very comfortable, shower terrific, and all of the appliances worked very well. The kitchen isn't super well-equipped but is very functional; in fact, I was able to cook one full meal there for a group of six.
The location is excellent! Lots of great restaurants and bars close by and an easy walk to the U Bahn-station.
I didn't have any communication with Phillipp during my stay, but he gave very clear instructions for finding the apartment and checking in. He also gave lots of great restaurant recommendations.
I will definitely try to stay here again next time I come to Berlin!