We had a great stay with our two small kids (1 and 4) at Angelo's place and would highly recommend it to anyone looking for a child friendly yet beautiful and very well located accommodation in Berlin.
The flat is very modern, while having the charm of a typical Berlin "Altbau" that was renovated with an attention to design. It has all the amenities you need, notably a great kitchen. And our kids loved to explore the kid's room toys :-)
Also, the cat Schnippy, was very quiet and discreet but after a few days, it warmed up to us and enjoyed some good cuddles.
The location is perfect, very close to the Ubahn, plenty of parcs and playgrounds around and of course Schillerkiez with it's restaurants, cafés, Saturday markets etc.
Communication with Angelo was easy and fast, and also the check-in and check-out were very straightforward thanks to the keybox.
A perfect stay!