I had a most excellent stay at Matthieu's. The place is clean, tidy and really feels like home. Matthieu was super communicative and easy to get in touch with. He was also very generous and let me borrow a jacket when my clothes were in the washer and I needed to make a dinner. The neighborhood is great, with many cafes, restaurants and shops within easy walking distance. Not to mention there is a tram stop right near his place.
Also, highly recommend taking advantage of his record player. There are lots of vinyls to enjoy, including Matthieu's own handcrafted ones.
I will definitely stay there again next time I visit Berlin!