we stayed at the campground last September and found it tolerable but nothing special. Clean bathrooms/showers, elec hookups and yes, you can take on water first thing if you want.
the gift shop/cafe is staffed with native americans and has some very nice stuff and the cafe offers (among other things) a really great indian taco big enough to feed two people.
at the east exit, on the north side of I 90, is a Museum of the Minute Man system of defense and it is very good if you are interested in the cold war era.