We did this 12 mile hike over two days back in June and it was absolutely spectacular. The hike from the top down will certainly test your knees particularly if you are backpacking, but at the bottom where it connects to the river there are some beautiful little camping areas for an overnight stay. The hike out along the river is a little treacherous but awesome nonetheless. At the convergence of Rattlesnake Creek and Ashdown Creek you can hike up Rattlesnake Creek gorge to see the two really beautiful waterfalls. It is better to leave your packs hidden somewhere at the convergence and then just hike up Rattlesnake Creek. Be sure to bring a water filter and plenty of sunscreen.