I picked this hotel for a short sight seeing break just before Christmas. It is conveniently located near to Checkpoint Charlie and the U-bahn. The stay felt a little strange on arrival compared to many since there is no reception; it is all done via their website, app or WhatsApp, resulting in a pin code supplied before arrival. It all worked just fine for me, no issues getting to my room at all.
There is a small lounge area inside the front door, but otherwise it is mostly just the rooms. Mine was one of the ones with a kitchenette - so microwave, fridge, small hob, sink and matching utensils. It is good for a small amount of cooking, but nothing very big. The room was a reasonable size, and bed was comfy. Had everything you might expect. It looked out into a light well in the middle of the building and had a door that could open into this which was good if it got too hot.
Not complaints, was a good place to stay.