This is a nice class I-II float that is a great alternative to the Sacramento River. Most of this run feels remote and is very pretty. As an added bonus in the late summer and fall, there are often large numbers of salmon in the river. The class II riffles give those looking for an introduction to moving water some interesting rapids to navigate with minimal hazards. It is much lower volume than the Sacramento, typically flows are 600 cfs from the fish hatchery to the outlet of the Thermalito Afterbay. Flows below Thermolito return are usually much higher. Flow levels do not seem to change the difficulty of the run, but higher flows will decrease your travel time.
The rivers is fairly wide with a number of class II riffles from the hatchery until after you pass the River Reflections Campground and boat launch. Past this point, the river braids into several channels. All rapids are class II and make this section the highlight of the run.
Other Information Sources:
Oroville-Thermolito Complex: Wikipedia
Feather River Fish Hatchery