Beautiful park with some amazing trails. Be aware that 4 wheel drive is required to drive to this park and that many rental companies will not allow you to, so I recommend checking with whoever you rent from first if you plan to try to go up.
This park has a single toilet and a couple of covered sitting areas for facilities. There are no grills or water, so if you plan on staying the night make sure that you bring food that you don't have to cook or have a propane cooker.
It also gets pretty cold up there at night. We stayed the night in June and it was in the low 50s when we woke up, so make sure you bring clothes and bedding to keep you warm because you will have a bad time trying to sleep otherwise.