Just back - No electric, water points few and far between, only one shower at each heated but clean bathroom, rumors of lots of ticks in season, walking trails nice.
Map for reservations poor - 'B' loop not many nice spots, 36, 54, 57, 60, 79 ok. 'D' loop better, 134, 138, 140 ok, maybe others too. 129, 130, 136, 137 and 141 lousy - Just wide spots in the road. Many sites are crowded in.
Why go there?? $20/night, drive to nearby DC metro at College Park (too far to walk) - door to door, about one hour to Smithsonian. Off-season, the CG was not crowded at all.
Using headlamps a lot at nite for reading, no electronics, and furnace only intermittently to keep comfortable, and 'off' after going to bed (30 deg for two of our 4 nites) still had 3 lights on battery meter at beginning of 5th and last day, 2 lights had appeared at one point late on 4th day.
You get what you pay for, but we are excited about going back there during the off-season. Summer in Washington without air conditioning is miserable.