There are two types of campsites at Upper Sage Flat. The first are lovely shaded sites with the rear of the site adjacent to Big Pine Creek. They have tree cover but are really open to the neighboring sites. Honestly, would have thought they were pretty great if we hadn't stayed at nearby Big Pine Creek Campground (check it out).
The second are the sites on the roadside and they are HOT AS BLAZES. There is almost no shade and they are basically just dirt/sand/rock pads. It's like being in an entirely different campground. Strongly recommend using Google Earth to check the site you're reserving (or first come, first serve if at (lower) Sage Flat campground.
If you're in the river side sites you'll love it. There is a bridge over the river that leads to a trail heading north to the Big Pine Creek Trailhead. You can also walk up the road but the trail is a more interesting option. Plus, it is the narrowest part of the trail you'll run for about 5 miles. That's a good thing because if you make it that first 1/2 mile you'll be fine the rest of the way when it opens up into some pretty incredible trail after passing through Big Pine Creek Campground and Glacier Lodge Cabins & RV park.
Decent pit bathrooms but right in the sun all day so much nicer in the mornings than evenings as far as flies and smell go. Bear boxes, fire pits and picnic tables. ***So basically a 4 if you have river side and a 2 if not. Maybe a 1. Location alone is worth 2. Yep. At least that. But really, try to stay by the river.