We loved the decor in the apartment - it was much better than staying in a dull white or magnolia box and as has been mentioned before the kitchen is very well appointed.
There are loads of tea bags in the kitchen left by previous guests - we brought our own which in the event was unnecessary. There is a supermarket (Penny's) just around the corner - whilst we used it for basic foodstuffs it seemed to have everything you could want.
The location is great - close to the underground - a weekly ticket works out to be great value (and ticket machines translate to English so its dead easy). We ate at a different local restaurant each night for the 4 nights of our stay - there is a good choice, Eberts was our best / most authentic German meal.
Finally having the kids in their own bedrooms was great, and the rooms were all big, bright and airy and even in the heatwave (30-34c) didn't get ridiculously hot.
Overall we had a thoroughly enjoyable time - thanks Serpil and Ariane!