We had an absolutely terrific time at Richie's stylish, modern, spacious, well-appointed, wonderfully situated apartment, which is located on a quiet street close to everything that matters in Mitte. Everything about the apartment was exactly as advertised, and the price was eminently reasonable for the space and the location. Two spacious, beautiful bedrooms (each with their own immaculate bath) are separated from one another by the lovely, tasteful central living area. The bedrooms and living area have high ceilings and floor to ceiling windows and doors, giving loads of light and wonderful breezes.
The building is new, architecturally appealing, and quiet. It is located in a part of Berlin that was just on the east side of the Wall, so there are lots of interesting remnants of divided Berlin within easy walking distance. Richie's apartment overlooks the central courtyard area, giving one the feeling of being part of a community. Check-in was easy, at the concierge's desk, and the concierge made herself available to help with questions about the apartment building and where to buy groceries.
There are grocery stores, bakeries, and restaurants close by, and we especially recommend Esszimmer, right across the street (fantastic food, despite somewhat easygoing service). We rented bicycles (at Fahrrad Frank, on Torstraße) and rode absolutely everywhere. Many Berlin residents get around on bicycle, so that mode of transport is fast, easy, and safe. One must get to know the rules of the road, and you might consider bringing your own helmet rather than paying to rent one. U-Bahn stations are a five-minute walk away. Tegel airport is within 20 minutes by taxi and a bus from Tegel drops you at the foot of Richie's street, a 10-minute walk from the apartment.
Communication with Richie was a snap, and he always responded promptly. To English-speakers who want to visit Berlin but know no German: you can get away with it, of course, but if you learn just a little bit of German, you'll feel more at home and you'll be able to connect with the people and the place more directly. Visitors to Berlin or to any part of Germany for that matter, should read up on the country's somewhat complicated recycling system, so you'll be able to do your part.