We spent two nights here with friends, one twin, and two double rooms. Each room was very generous in size, with great big windows onto leafy quiet street. Our bathroom was huge (no bath) with massive splashback shower. Small minus is they had zero interesting tv english channels, however we were hardly had tv on so it didn't matter.
I thought the location was super, and we spent the first day strolling around Berlin. We were able to walk to our restaurant first night, Borchardt (highly recommend also) and Cosmo have bikes for hire (12euro) which we did all day Sunday, which is an awesome way to see a city, we covered east to west and more.
The hotel is as at it looks, modern and clean, we had breakfast on Sunday morning and it was also very good.
The staff couldn't have been nicer throughout our stay, and when we go back next year, we will stay here again.