The problem for us visitors from the UK is that we tend to make comparisons between the very high quality of campgrounds we find at home, with the (generally) less well maintained ones we have found in the USA.
Having said that, KOA Fredricksberg is amongst the better places we stayed during 2 weeks of travel from Florida to DC in a 25ft rented campervan.
The setting is excellent, amongst trees by a lake, the bathroom facilities clean (if not as modern as we are used to) and the reception office staff friendly and welcoming.
Our pitch was not as level as it should be and a longer vehicle would have had difficulty getting level without use of chocks.
The campground is convenient for access from the I95. We stayed 2 nights and explored the local area during the one day spare. We returned after dark (it was November) and even though we knew where we were going, it was not too easy getting into our site. There is little or no campground lighting.
I know that costs are different between Europe and the USA - some things cheaper, some more expensive - but in the UK, France, Spain, portugal, Germany, I would expect to pay half this price for much, much better site and facilities.