Although kayakers would tire of the flat stretches, and beginners would be frightened by the rapids, for open-canoeing whitewater tripping, I don't think many rivers compare to this. You could spend several days on this river, depending on put-in and take-out - we did the "bridge to bridge" run over 2 days. Basically a medium-low volume river with lots of grade II-II+, with a few grade III sections that are fairly easy to scout.
If done in summer, the water is warm, but flow can drop too low in August if low precipitation. The environment is considered to be part of the dry interior forests (which is now heavily infested with the mountain pine beetle). The character of the rapids is long successions of pool-drop, with an interesting canyon at one point where the river narrows to a four foot slot (calm water no less).
If anyone is interested in coming up for this, you can email me. I would be very interested in doing the stretch to the Fraser River, which is more of the same but slightly more challenging.
Camping on river.
Southwest of Prince George, past Baldy Hughes, onto the Blackwater Road all the way to the River. Put in on Batununi Bridge, take out Blackwater Bridge.
Highly recommend the Northwest Paddling Brigade's Guidebook.