Helmut's place has everything you need for your stay. Appartment has supermarkets, restaurants, U-banh line 6 and coffee shops within 5 min walking.
Helmut always answered my questions in a short time, which i appreciate a lot. If he can not make it to deliver keys, there will be another person who is really nice and helpful.
Neighbour is quiet at night however it is safe. You can come back alone on foot.
I reccomend Helmut place :-)