I took the creek class at NOC a couple years ago. Its was pretty good. We ran the the Doe, Wilson Creek, and the Upper Green. First day was flatwater, some basic moves on the raging class II nantahala (got skunked on water), and a fun park n huck on big kahuna on the nantahala cascades.
My impressions of the class...
-NOC lodge, food, shuttles, gear etc. is primo. They have a great set up. They have everything you need and really take care of you.
-The people at NOC were great. Top notch folks.
-The level of difficulty of the class was a less than what I was hoping for. We spent half our time on class III or less, but there was also not a lot of rain, so we were somewhat limited. Wilson creek and the Doe were good.
-Would be a great class for a class III/III+ boater looking to step up or a tenative class IV boater.
If you are boating class IV in colorado, I'd think about Lelands class. He has got rave reviews, and when I checked it out, it looked like he had a more advanced class than the NOC.