The apartment is very modern and clean. It was cosy and warm, especially for the winter. Natalia is a very welcoming and friendly host and gave lots of information about local transport etc. The area is quiet and Alexandra Platz is about a 25min walk or a quick tram ride so the apartment is in quite a good location.
Note: you have to pay a tax for staying in Berlin when you get there but it's only 5% of the accommodation price.