I love the River. This is the disc I throw when I want a very precise shot, and the range is too far for an approach disc. My nick name for this disc is the "long range Buzzz". The river will give me a predictable slight hyzer (curved) flight path over the entire flight, with only 5-10 feet of side to side action. This lets me throw it down tight fairways bordered by trees. The high glide on this disc gets me some extra range without using excessive power that could decease my accuracy.
I have this disc in three different plastics. Opto, Golw, and Opto-X, Each of these is progressively more stiff/stable. This allows me to get the same flight path in different wind conditions just by changing the plastic.