Our Stay at Katarina was really pleasant. The apartment is really nice, clean and in the center of Berlin.
We found the internet to be an issue major with our stay. We stayed in the apartment for around 3 months and for the whole while the internet could never be fixed.
Katarina explicitly said that she provides accommodations majorly to students and working Professional but sadly fails to understand that the internet is very important for both these genres of people.
Other than this Katarina has been really helpful and quick to reply. Except for the internet, you will find everything in this apartment top-notch.