The part that's fun in a whitewater boat is very short, about a quarter mile, but at 400 - 800 cfs the waves are good enough to surf and there are actually some pretty strong eddy's that make for good fun practice. The best part of the waves are right near the put in so you can surf and lap without leaving sight of the vehicle. Even the 1/4 run is great fun there is very nice trail streamside to hike it back to the top for another go. I've run it 4 times in an hour and had a ball. Its no Cache La Poudre but I can run it every week with out taking vacation time and its pretty fun.
Its located at the South Outlet Park on the Republican River just downstream from the Harlan Dam. You can check the flows ( at least a day old, so always always call the Corp of Engineers before you go.) This is the link to the Army Corp website that has the Dam Outflow number - you really need 350 to even do the run but can surf some small waves down to 250. If you can catch it above 450 its a blast and 800 is just sweet. Current Data for Harlan County Dam, NE
If you want to hit it sometime or want a little help with technique I can run you through most of what you'll learn in a beginner WW class, though you should take one for sure. PM with a number or email if you want.