Our stay was during what is called a heat wave in the Netherlands, 90 (F). The hotel has no AC at all, and the windows didn't open either... only a patio door, which didn't allow for any air flow. Our room has a split level, the second level was even more unbearable. We all slept in 5 minute intervals, and the kids slept on the floor to be cooler. I understand the hotel doesn't control the weather, but be aware that there are no provisions to deal with hot weather.
On a safety note, I do have quite some concerns. I did not see any sprinklers inside our room, to evacuate the room we stayed in without sprinklers, would be tricky at best. Especially the loft area of our room would be a serious safety concern. With only a narrow, unstable spiraling staircase, the loft is a serious safety concern for smaller kids. My kids are pre-teens, yet I still had to assist them to go up and down to avoid serious falls. A stay with a toddler would not be safe in the room we stayed in.
The reception desk closes at night, you cannot reach anyone. Forget about things like wake-up calls, or the maintenance department. The fitness area and indoor swimming pool also closed at 9 pm, with all hotel staff apparently going home for the night.
On positive notes, the breakfast that is included is quite nice, typical Dutch style with luncheon meats, sliced cheese, nice rolls, etc. Also, the town of Groesbeek is quite nice and quite; a typical rural small town, located close to beautiful nature areas.