Alex's flat is large and clean. It is located in a nice part of Wedding with a S-bahn station close by. Both the check-in and the check-out was easy and simple. While I did not meet Alex he was very responsive with his messages.
The architecture of the flat is a bit unusual and the fact that the toilette and the shower are so far apart is slightly annoying but nothing that can really affect your vacation.
All in all, I can recommend the flat.