Frank's apartment is really interesting and has everything you need. There are some cool lighting options, including a lamp for the disco ball! The bed was comfortable (we like a firm bed) and the kitchen was kitted out well. The buttons on the induction stove are a bit finicky but worked most of the time. Frank supplied us with some firewood so we could use the fireplace a few times, which was quite welcome after walking around in the cold Berlin weather! The location wasn't super close to the centre, but very convenient for transit; there was a bus stop just outside where you could catch 2 different buses, and the Sudkreuz station for trains/S-bahn was only a 8 min walk away. Transit in Berlin is amazing; we bought a week pass and could use it for all 5 kinds of transit. Frank was very quick to respond, and when we arrived he gave us a thorough tour of the apartment and had lots of advice and suggestions for getting around and places to see.