The flat is easily reachable from Berlin Tegel Airport by UBahn and Taxi. We chose a taxi as we were very tired after a 17 hour journey. The fare was only 22 Euros. Check in was smooth, and Daniele's representative Carmen, explained everything.
The flat is as described, quiet, and clean, and furnished well. It was close to the UBahn and bus route, which took us everywhere. There were plenty of shops and restaurants within 20 minutes walking distance. There is a direct bus from the corner of the flat to the main railway station and other tourist places.
The wifi worked well.
My only suggestion is to provide salt, pepper and some sugar in the kitchen. This would make a huge difference after a long journey. Also, I would suggest some more kitchen equipment such as vegetable knifes. Otherwise the place is perfect.