I stayed @ Hotel-Pension Bregenz in May 2014 for a week and was very happy with my experience. I've stayed there before a few years ago and was happy then, and was thrilled to see that the hotel didn't disappoint me this time. :)
The hotel is located in a relatively quiet part of Berlin - near Wilmersdorf/Charlottenburg in the western part of the city. It's about a five minute walk from a bus stop on Ku'Damm, so getting to the airport, to Bahnhof Zoologischer Garten and downtown is pretty easy. Despite being so close to Ku'Damm it's very, very quiet in this hotel - perfect for solo travelers, families, couples. A couple of restaurants are nearby too. The only thing that woke me up was the birds in the garden below, aside from that, you wouldn't really know you're in a large metropolitan city.
The accommodations are pleasant, nothing sexy, but very clean, very comfortable bed and large bathroom. Breakfast was pretty good - typical German spread (some meats, cheese, yogurt, juice, breads, coffee/tea) and served from 7:00am until 9:30am. The hosts are a married couple with two children, they are very helpful, pleasant, and it really seems like they want you to enjoy your stay with them. My only gripe would be that the internet connection was spotty - wouldn't depend on high speed 100% of the time.
Highly recommended for anyone seeking an affordable, quiet, place to stay in Berlin. Will definitely be back!