Just got back from a short trip to Berlin staying in Eliavs flat. Eliav was very welcoming, took time at the start to chat to us and give us tips which was great. The flat is in a great location - especially if you are vegan/vegetarian. Lots of options for food and a great market with a vegan supermarket and cafe upstairs. The U-Bahn is a short walk away and there are also buses nearby.
The flat itself is comfortable, warm and has everything you need. The kitchen has the basics for cooking - the only thing it's missing really is a toaster. The bed is very comfortable. The bathroom is fine - the shower was occasionally difficult to get hot but this was not a major issue. One other point - the flat is on the 5th floor with stairs so you get a good workout!
All in all a great trip - I would recommend Eliavs flat mainly for the location and the value for money.