I come to Berlin often and I stay in Friedrichshain as it is closest to my work. The mattress was a bit stiff, but other than that this was a good set-up. The location is great near the tram and heart of Friedrichshain. It was clean, internet worked perfectly fine, and had the basic amenities. Most importantly this unit was not street-facing, so it was not noisy, which is something I struggled with at other places in this area.
Definitely recommend.