Pros:

• No fee!
• Sites are well spaced, so you aren't right on top of your neighbors. We were at the end of the line, so we were well secluded from the rest.
• Vault toilets were as clean as can be expected for as late in the season as it was when we camped. Either was a reasonable walking distance from any site.
• Our spot was one of the bigger ones, with fire pit, (2) picnic tables, (2) tent pads and plenty of parking for an RV and vehicles.
• Short walk through the trees to the river. Can hear the water from the campsite!

Con:

• Traffic noise from the East Rosebud Road was noticeable, but not terrible.