Fair warning, if you are over 5'6" you will soon realize the space is very, VERY short. I am 6' tall and I felt really cramped. I also had to sit down in the tub in order to shower.
Also, as mentioned in other reviews, the apartment is at the very top of the building. Which means you will have to climb quite a few flights of stairs in order to reach it. If you have heavy luggage, beware!
But other than that, Niels' place was very pleasant. The space (although short in height) was plentiful for two people. The windows are operable, allowing in fresh air and helping cool the place off at night. Niels was very easily accessible over Air Bnb messaging, and even gave us a welcome basket of goodies.