We booked Fema's place about a week before we came, because our other host had cancelled on us, but I feel it was a blessing in disguise, and we got a much better deal on this place.
There were 3 of us that stayed so we all slept very comfortably since there are 3 big beds. The bedroom is huge and you could probably even put another bed in there, but it was nice to be able to take advantage of the space for all our shopping and clothes ;)
The flat comes equipped with tea, coffee, and fully loaded cleaning station in the bathroom. You can tell this place was designed with traveling guests in mind.
We were hesitant of the location as it is a bit out of the core, however the subway is a 5 min walk away and gives you access to everything, I think i might have seen more of Berlin do to this fact because i did not just stay in one or two areas the whole time.
If you get hungry at night be aware it is hard to find places to eat late night in Berlin, so stock up the fridge, or walk down the road a few blocks to Wedding and you will find late night Turkish places to fill your midnight craving.
The kids were not much of an issue, but in the bedroom i did hear the neighbors through the walls, but it was nothing disruptive, just bring ear plugs if you are a really light sleeper.
Overall this was a fantastic place to stay, and I highly recommend it.