Stayed with Helen for one month. All in all, my time here was great. Helen was a very helpful host and responded quickly to any of my texts. The apartment itself was nice, clean and had everything one could need for a longer stay, especially the kitchen was adequately furnished and had everything to cook proper meals! The location itself might just be the only downside (though it is very clearly advertised that the apartment is located on the edge of Berlin). Even though it is nice and quiet and within 5 minutes you can reach sprawling woods on the border to Brandenburg, as well as a big supermarket (Edeka) also within 5 minutes, it takes rather long to get anywhere (fortunately, everything the tram lines 62&63 right infront of the house take you to the S-Bahn Station Köpenick, from.there it's a direct line to the center). All in all, i would absolutely recommend Helen as a host and her Appartment, especially if you are staying longer.