My wife and I recently stayed here for the first week of our honeymoon, and we could not have picked a better spot to stay. We stayed in a one bedroom apartment that was larger than the place we live in normally(Quite a feat when staying in Europe). The place was nicely furnished, and we were amazed at how everything in the living room either reclined or transformed into something comfy to lounge on. The kitchen was fully stocked, and they even made sure we had detergent to use for the dishwasher.
That was another thing that made this place stand out, the staff and service. Now we're not talking about a maid that comes and cleans your room every day as this is very much your apartment while you stay here, so treat it as such. Silvia, who was very friendly and informative, gave us tons of great info about the area and city and went way out of her way to make sure we had a great experience. So much that we made sure to bless her with some wine and chocolates. Thanks again for helping make our honeymoon so remarkable. Be sure to get a map from her. It was more helpful than any map in an application or tourist guide. Trust me, we had them all. Also, as many have said before, the location cannot be beat. Located right in the middle of Berlin, and less than a stone's throw from transportation to any place your heart desires. Yes it is right by the subway, but you can't even hear it because the sound proofing is amazingly well done. This was something I myself was skeptical about.
That brings me to the con's, which are few and minor. The bed was a little hard, but wifey and I are spoiled on that one, and there is extra padding in the closet. The shower leaked a bit because it doesn't fully close (interestingly we found this to be the case at 4 out of 5 places we stayed throughout Europe), but the bathtub was quite roomy. Finally, they only take cash and I never like having to carry more than a couple hundred dollars on me at a time, but that is what it is.
Overall, I highly recommend anyone considering to stay here to do so. For the price it cannot be beat, and it was nice to have a place to call "home" while in Berlin.