My wife and I stayed at Karen for 4 nights. And we had the best experience imaginable.
Location is perfect. Either walking or biking (Karen has 2 bikes for visitors to use, best way to explore the city).
A food market around the corner everyday (except Sundays).
Restaurants and everything else you might need.
The apartment is on the 3rd floor with typical Dutch steps (very steep), very well organized, stylish, clean, nice balcony, hot water immediately in the shower.
Karen is right downstairs and very reachable, nice and generous.
Everything you look for in an apartment when traveling.