The flat is bright, spacious and clean. Easy walking to a few different metro stops. Yummy places to eat close by or quick metro stops away. Easy to get to and from sites in the city.
Robert is an excellent host and really goes above and beyond to make you feel comfortable and at home. Always available for info on Berlin or just a friendly chat. If you get tired of humans you can hang out with his lab, jack :)
We stayed for 4 days and had a blast exploring Berlin during the days, hanging out at "home" at night. You won't want to leave!!