I came here on Sept 27th to fly fish Rock Cr, not to hike, so this review will be for a niche audience.
Thia site is really isolated. The parking lot had only 1 vehicle in when I arrived and when I left a few hours later after seeing no other people. So for solitude, peace and quiet, 10 stars. There isn't much of a trail along the creek but fishers had tramped down some of the tall grass to various spots on the creek bank. What I assume is the main hiking trail is marked and reasonably easy to see but hikers will still want a map or GPS (I didn't have cell coverage).
The creek was low but a bit discolored, probably from some recent rain. It is easy to wade and can be crossed on foot in most places.
The scenery out here is right out of a western movie - rolling hills with basalt outcroppings as far as the eye can see, tall grass and a few weathered buildings. Walking and fishing in it is a great antidote to the somewhat monotonous experience of driving through the Palouse at 60mph.