I can't recommend It enough. The apartment is absolutely gorgeous, cosy and warm (important if you're visiting during winter). I found it in a spotless condition. The neighborhood is about perfect. You will be a few minutes away (walking) from a pharmacy, supermarket, bus and u Bahn stations, as well as centre of kreuzberg where you can find nice bars and restaurants. The best part is that you get the best of both worlds, given that right outside the building you have a big park and the neighborhood is extremely calm.
Graciela was out of the country, however she coordinated with her neighbor who took care of our check in. Super easy and straightforward.
The Communication with Graciela was flawless specially considering the 7 hours difference. She was very helpful and always got back to me within a few hours or even minutes, both before and during my stay.
Again, I can't recommend it enough. I'll definitely try to book it every time I go back to Berlin.