This is a great place to stay, with Oz as an amazing host. It is clean, well-maintained, and incredibly convenient. The neighborhood is a bit sterile -- it is new and there's some construction noise around as the whole district seems to be re-building -- so it is not "old Berlin"; but a short walk or bus or tram or U-bahn will take you wherever you want to go, easily and conveniently.
The apartment itself is marvelous and if you want a quiet residential place to rest after a day out, it is really wonderful. Can't recommend more highly.