Alexey is a very nice host and his appartment ist absolutely recommendable! We found it extremely clean, modern and the location is ideal. There are two underground stations close, which make it possible to get everywhere in short time. The Berlin Tiergarten with the most popular sights is even reachable with a nice walk. You can find some nice places to eat really close to the appartment in Akazien/Goltzstraße.
Alexey is happy to give suggestions about what you can do besides the usual Berlin 'sightseeing'. Since he mostly works or is out himself and absolutely respects privacy, you will often have the whole place for your self and can get rested. We really enjoyed our stay and would definitely come back!