If you visit Theodore Roosevelt, you likely want to see the bison the park is famous for, and if you stay at Cottonwood, you likely will. We did--up close. One passed within about 10 feet of our campervan (which we'd jumped into with our dog, as the bison started to approach). What a thrill. We wondered if it was the same bison we'd seen grazing about 50 yards away the day before and the same one who'd left muddy hoofprints all over the campground. 

We didn't love the campground itself as much as the other reviewers did. The sites are decently spaced, and many of them are at least partly shaded. The bathhouse near our site was newish with flush toilets (which my spouse always loves). 

So why not five stars? The camp host committed one of my pet peeves, which is not enforcing the generator quiet hours (8 pm to 8 am here). A camper near us was using his generator till at least 10:30 (when I finally managed to fall asleep; he might've been using it even later). Too, the campground was buggy--as buggy as I've experienced in the West (which I usually find to be much less buggy than my homelands in the muggy, wet East).