This is the best place you can ever wish to stay in whenever you're in Berlin. Very clean apartment, very spacious too with all the necessary amenities that you'll want to have in an apartment.
Available wifi, beautiful touches, great location, technologically advanced check ins, overall better experience.
2 things to keep in mind though,
1. During our stay there was no microwave so when we needed to warm something up, we had to use the oven and 2nd, we had to make a down-payment of €200 before we can enter the room for any accidentals. (We didn't know that beforehand and some people may have a problem with that so keep that in mind. And 24hrs after checkout, you'll get your money back which we definitely did).
I will totally and wholeheartedly recommend their apartment for anyone because I don't think you can find anything better than what they offer.