Location of the apartment was great, access to everywhere with Alexanderplatz less than five minutes walk away. It was a very clean, modern apartment, perfect for a couple but slept three of us easily. Zoltan was happy to meet us late at night when we arrived in Berlin and was always reachable by message or phone call.
Unfortunately, there were issues with the shower while we were there which were left unresolved for a little too long. In the end we had to move apartments for the last two weeks of our stay, however Zoltan managed to find us a brilliant place to stay so we were never left out of sorts and were still able to enjoy our full time in Berlin.