I'm rating this hotel as a 1 out of 5 for a few simple reasons. (1) The internet/Wi-Fi is awful and was non-existent at times. Even after informing the staff of this, nothing was done, an unacceptable excuse of "too many people in the hotel were on it" was given (Okay...so upgrade your infrastructure?) and the same problems continued. That's ridiculous in 2019. (2) The rooms didn't have a kettle, extra sheets, water bottles or really any nice gestures/touches. Toiletries were never refilled. Decoration was sparse to non-existent. Minor damages and stains were noticeable. (3) Only one key could be given per room even when an extra was requested (and they are just plastic key cards...). This was nonsense, made travelling with others very difficult and is not the standard policy in Germany.
In short, unless this hotel is being offered for 50 Euros less than alternatives, I would not recommend it. There are lots of great hotels in Berlin at very reasonable prices that will give you much better value.