Family and I stayed here in late May for three days. We have stayed in the past in June and July as well. 

Campground is south of Big Sky, so if you need to buzz into town for any last minute supplies, it is only about 10 minutes up the road and has everything you could want. 

Campground has both standard and electric sites. We have a small camper and scored one of the spots near the south end, which is also close to the Elkhorn Creek Trailhead. Best sites are obviously closer to the river, with those at the far north end or south end the best options. Some of the southern end options on the east side of the campground road are tucked up pretty tight to the hillside, and are not as desirable of a location. 

Pros:
Beautiful setting, easy access to hiking, cave exploration and rock climbing.

Later in the summer, the Gallatin river provides good fishing opportunities. 

Yellowstone Park is about 40 minutes away. Tons of hiking options within Gallatin Canyon, all accessible via a short drive if you want something away from the campground. 

Great camp hosts, who check in with everyone, have firewood, and ensure everything is good to go. 

Potable water spigot, bear proof dumpster and recycling are all available near the entrance. 

Cons:
Being that the campground is near the river, which also parallels the highway, road noise is pretty common -- big semi-trucks hitting the rumble strips take something away from the peaceful setting, but it is not a deal breaker. That really is the only minor gripe. 

Highly recommended overall for tent or RV camping.