My wife and I spent a week in Karsten's flat.
It was great, nothing less. well furnished and designed. checking in and out was simple and fast.
The flat is situated 1 min walk to an underground train station, easy to navigate close to all central attractions.
Its clean and in a quiet area which allows you to relax after a day of action in the city.

Karsten was a great and accommodating host. communication was great and helpful.

If you can grab his flat go for it, you wont regret :)