This flat is well-appointed with many amenities including stove/oven, microwave, kettle, toaster, refrigerator, dishwasher. There were plenty of linens and towels for those in our group and some items for our use (toothbrushes, travel sized toiletries, etc). We did not encounter the wi-fi issues others reported, which was nice. There were many homey touches including Christmas decorations.
One bedroom has a double bed and the other has two single beds that can be pushed together. There were radiators in each room that you could adjust for your comfort. The location is in a quiet, residential area with ample street parking as well as a bus stop within a few minute walk. Berlin has a robust public transit system, so it's helpful to be on that bus line. The street itself was quiet, which we appreciated as we were visiting with our young son and it allowed him to sleep undisturbed.
There is an occupancy tax due upon your stay. It's not listed in the listing so be advised this will be expected (https://www.berlin.de/en/tourism/travel-information/3298255-2862820-city-tax-in-berlin-who-is-to-pay-how-muc.en.html). It's 5% of the cost of your stay I believe. Also, some of the items in the flat are not included and there is a price list for these items on the back of the wi-fi instructions (I believe it's 1 EUR for most of the drinks and 2 coffee pods for 1 EUR if I remember correctly).
Katarina and her husband were very pleasant and greeted us at check in despite our late arrival. We really appreciated their flexibility. They were also very responsive and quickly answered any of our questions.