Unfortunately, this apartment is in a lovely old building, which means there is no lift. As the flat is on the fifth floor, this becomes an issue very quickly. Still, nothing the owners could ever do about that. Be warned that only cash payments are accepted, which I doubt many people would expect these days. As a result, I paid as much as I could on my first day, and the rest on the second which left me with virtually no cash for two days (at one point it was said that I wouldn't be given the keys until I had paid in full - fortunately that did not happen). While this was inconvenient, I suppose I should've checked whether card payments could be taken before I arrived, so I take some responsibility for that. On the other hand, when the owner came for the second part of my payment, it appears that he didn't consider the possibility that a tourist from a non-Eurozone country might not have the exact amount. As a result, I never did get my six Euros change. Not a huge amount, but it did leave a bad impression. Also, the downside of the tram stop being so close is that the trams do make a bit of a racket at night when they go to thew depot for the night. However, after the first night I can't say it was a problem.
All in all, I would have happily stayed there again if it weren't for the fact I never got, or was ever offered, those few Euros change. The small points make a LOT of difference. Hopefully the owners will ensure that never happens to anyone else.
I stayed in the apartment on Malmoer Strasse, so I can only speak for that one. For the money, I think it would be hard to find a larger apartment. The front room and bedroom were vast, with good views down on Berlin. The trams stop practically outside the front door of the building, and are regular and frequent, giving easy access to all of Berlin. The actual area is very pleasant - not particularly loud but fairly lively. From the bedroom window, there is one of the few surviving sections of the Berlin Wall easily visible, so you don't have to travel far to cross that off your list of things to see! There are a few decent supermarkets and some pleasant cafe/bars within easy walking distance.