This apartment is just located in the tall tower next to Den Haag HS station which makes it very easily to be found by public transportation. But if you drive, my suggestion is to put the address "van maanenkade" because you will find the parking of the Penthouse there and the sign of the way to the Penthouse in that parking leads you to the reception easily. This tower is on the conor of Rijswijkseplein and Rijswijkseweg, not difficult to see but the Rijswijkseplein from HS station direction is a one direction way which means if you come from outside of Den Haag-the A12 direction and took the 3rd exit, you can not drive into Rijswijkseplein, and the Red White house in the explaination is a bit confused. So just use Van Maanenkade as your destination address, it's a small street with a canal by a big red house with a bit white signs where you will find the parking just behind the house.
As for the apartment, I have to say it's so cool to see the city from above. Our only pity is we forget to go to the 42th floor to make a panoramic view...
There's a AH supermarket on the other side of HS station, around 1 or 2 min walking from the tower. And if you walk a few steps further, there are several restaurants as well. But the tower is not far from the city center, we went to China town for a lunch, it's only 1 km by walking, or 2/3 stops by bus. You van buy a day pass by 6.5 eurp in the HTM office next to the HS station to visit the city by bus and tram, very convenience.
The only thing that some people may mind is the television is really small but for us it's ok because we didn't use it...