PROs: Jürgen was very friendly and quick to respond to emails. The key exchange with his friend went perfectly and there were fresh bedsheets and towels ready in the flat. The location is very convenient for the UBahn, buses, and grocery store open late across the street. Wedding itself is not one of the great Berlin neighborhoods of course; you'd stay there for the convenience of transport rather than for atmosphere.

CONs: The flat unfortunately was rather dirty. It seems like it hasn't been well maintained -- mold in the shower, dust bunnies in the hall, crumbs dirty dishes and stained sinks in the kitchen. The cleaning company hired to clean between guests wasn't doing a good job, and as Jürgen is out of the country he didn't know. He was however understanding about the situation and refunded me the cleaning fee, hopefully the next cleaning company will be better.

OVERALL: if you are looking for somewhere practical/affordable that's convenient for the airport and transit around the city, the location is good and the flat is fine, I can recommend it. If you are looking for a charming, atmospheric home base for a fun/romantic Berliner visit, or if the dirtiness would be a turn off for you, it might be better to look elsewhere.