Playpark was amazing at higher flowers (around 4,000cfs). It was okay at medium flows (2,000cfs).
Now that the river has dropped to below 1,500 cfs, it hasn't been very good. The engineers are trying to figure out wave shaper combinations to make it work best, but the holes created have been very tight and steep... not good for much.
I'd ask Idaho River Sports for some private play boating instructions. Not much to teach, really... once you have your roll and figure out your edges it's just a matter of getting a feel for what the boat does in a hole and how to lean, paddle and rudder.