Assateague is a wonderful place to backpack or car camp. It's a beyond beautiful location with great amenities and very kind employees. Just watch out for the mosquitos if you're camping bayside - you might leave looking like you have chicken pox.
The facilities at the campground are top-notch. The sites, while close together, are generous in size. The state park employees are very helpful and friendly. The only downside is that the beach bathrooms are, well, beach bathrooms.