My family (husband, I and 2 teenage kids) stayed in Marls's apartment for 3 nights from Friday to Monday. We would not recommend this place for families that are seeking rest between busy days visiting Berlin attractions.
It is located right above the restaurant and all smells from the kitchen are coming up from the kitchen. One bedroom is facing the same street and the noise is unbearable until it closes. Unfortunately for us, we were staying there during the busiest nights for the restaurant - Friday, Saturday and Sunday. We had to swap bedrooms with kids to give them a bit of a rest at night, but the other bedroom is facing the internal courtyard that is used as a smoking place by 2 houses. To add to the story, the bedding was awful - old and stinky, very uncomfortable to sleep. Purple towels had bleach stains all over, I could not believe that and took photos. Very slow, basically non-existent wifi was the least of our problems, but worth mentioning for future tourists.
Location of the apartment is inconvenient. Ubahn station is very close, but it leads to nowhere directly and it takes at least 30 minutes to get to the central station (even it is less than 3km away as mentioned in the description). Due to roadwork on the street, it took the same 30 min from Hauptbahnhof to the apartment by taxi...
All in all, we will never be back to this place and would not recommend it to our friends.