The apartment was clean, convenient, and perfect for our weeklong stay. It had all the necessities: a washing machine, cookware, wine glasses, a hair dryer, and probably much more that we didn't end up using. The location felt very safe for us (two girls) and was very conveniently located to grocery stores, restaurants, bars, and transit. Martin was clear and communicative and gave us a map with suggestions regarding the immediate neighborhood when we checked in.
In particular, if you're interested in the museums, the bus stop to Museum Island is steps away from the apartment, and the U7 and U8 is a few minutes away. The ambient noise outside wasn't distracting for us—we kept the windows closed since the weather was getting a bit brisk and slept soundly each night. There are two lofted beds which provided enough privacy for the two of us, and I'd really recommend staying here if especially if you're planning a semi-long trip in Berlin.