Myself and my girlfriend stayed in Nassa & Nader's place for 4 days as we explored Berlin. Their place was in a great location for this as it is situated very close to the U and S bahn subway and train lines. There are also some great cafes just up the street from the house where you can have a nice breakfast and a coffee at the start of your day.
As hosts they were very helpful with any questions and very accommodating in terms of check in and out times.