The apartment had all the basic amenities that we needed for our base to explore Berlin. Beds and linen were crisp and clean, the apartment was well ventilated by the balcony, and shower water pressure / temperature were excellent.
The place may look fairly plain with not much interior decoration, but this should suit travellers well as it means the place is tidy and practical - we think this is a positive as it made it easy to make sure we left nothing behind.
Importantly, the location is excellent as it is less than 5 minutes walk to the U and S-Bahn, as well as tram, and then only takes a few minutes on the U to Alexanderplatz, for example. The availability of all transport options made getting around a breeze (compared to some places we stayed before).
We ate every meal out (it's Berlin!) - so we cannot comment much on the kitchen amenities except to say it looked to be spacious enough, although instead of eating in we highly recommend Bilakis (around the corner) for a quick bite, or Klements restaurant (just outside) for a sit down meal - both are excellent.
Overall, extremely satisfied and would recommend to anyone, can't stress enough how great the proximity to public transport is! Will definitely look to book again next time we are in Berlin.