Magnificent view from the 5th level! The dropoff is not fenced and there is no barrier of any sort, so please be sure of your footing, as it is an 800 meter drop. Having seen many, many temples prior to Preah Vihear, it's not the best, although some parts and carvings are well preserved.
I went with San Park, who has grotten good reviews by other travellers, and I was also happy with him. It turned out that two other people has booked him for the same day, so I ended up paying only USD 55, + 5 for the motoride up to the entrance to the Temple.
If you take a car, it's USD 25, but there's really no need, as the road is absolutely fine asphalt all the way,but for about 10 meters or something like that. The moto waits for you, so it's USD 5 / return.
Bring your passport, otherwise they will not allow you to buy a ticket. I don't recall the price.
You can buy food and water up at the entrance area.