I highly recommend Nitya's place! The location is really nice, near all the transport (s bahn, u bahn, busses, trams, etc.) and also very close walking distance (like 10 minutes) to the busy/hip part of Friedrichshain with restaurants, bars, flea markets, shopping, etc. Lidl, rewe, aldi all within a 5-7 minute walk, and on the street itself there are several nice, basic neighborhood takeout restaurants and neighborhood bars.
The apartment is really homey and nice, and has everything you might need. The room is basic, but large (exactly as advertised) with a nice balcony overlooking the small park across the street. It's in a safe and fun neighborhood with a lot of young people and families.