Great location, amazing amenities(huge pool, game room, snack bar, camp store, coffee shop etc.), and friendly employees, but these are where the positives end. I've never stayed at a KOA/campground where the sites were so unlevel, close together, and the whole infrastructure in need of repair.
The Historic trench section is nice in the trees, but the roads are crumbling and too small for most RV's. If the person across from your site is already parked, good luck having enough room to back into your site. Our site was so unlevel that I was not able to get the RV leveled the entire weekend. Looking at the surrounding sites most campers were jacked high on blocks or sloping significantly. The section of sites were on a curve/semi-circle, which caused the site beside ours to be even smaller. We had to move our picnic table to give space for this person to back his camper on the site. They were unable to get even close to level so they didn't put out their slide. There is a new section to the campground out in the open whose sites are more level, but they are even closer together than the section we stayed in.
In addition to the poor sites, little enforcement was done regarding monitoring the number of people on the sites and the partying going on. A nearby site had 15+ people on Friday night partying and carrying on until 1:30AM until a fight broke out. They had a boombox on the bumper of the camper and blasted music all evening. After hours any vehicle can enter the campground as there is no gate. Cars/trucks pulled up to the party sites, who just drove in to party. I know calls were made to the office as neighboring campers stated to us. On Saturday night, the group wasn't quite as rambunctious, due to a visible presence of staff driving by, but with a campground this size, regular monitoring and shutting down of quiet hour violators should occur pre-actively. Harpers Ferry KOA could be so much more if they would invest in site upgrades and rule monitoring. We will not return.