We enjoyed our stay at Jaspers. The apartment was clean with lots of natural light. Great location, very walkable and surrounded by some lovely restaurants. As others have mentioned, be aware of the stairs, we had large luggage but we managed ok. Climbing the stairs does lead you to a lovely view especially the rooftop!
Checking in did take some time as there is no key safe but Jasper was responsive and polite when we called him. Unfortunately we did have to wait outside for around an hour, thankfully it wasn’t raining. WIFI is very weak and often drops out with the network disappearing completely but is better on the top floor of the apartment.
Overall we would recommend Jaspers place for a stay in Amsterdam. It was in a great location, and clean.