Nice stay in a comfy attic. You may have a bit of difficulty getting luggage up the stairs but even with 3 big bags me and my friends didn't have a hard time.
Space: Comfortable environment, pleasantly surprised to have so much natural light even on rainy days. Kitchen facilities are sufficient- my suggestion to the hosts is perhaps to get a bigger table of some sort which can be better used as a space to work/eat. But otherwise no complaints- beds were comfortable and place was well-decorated.
Location: City centre is walkable, train station not so much. You're about 5 minutes away from tram stops that take you into the city/train station (16) and Schevenigen (1, iirc). Neighborhood felt safe, and close to a very nice canal. Places to eat nearby- and a nearby market I can't really remember much. The Albert Hejin XL3 minutes away is a bonus.
Overall, I'd stay here again if I were to visit Den Haag.