Why do most people here hate the waterfall? It looks gorgeous in my opinion. What is it you don't like?
http://www.youtube.com/watch?v=JSRtYpNRoN0&feature=player_detailpage#t=85s
It looks flat, plastic, horrible texture, no animation, no reflection, no transparency. Same repeating movement all the time it seems (can't be 100% sure though since it's only a few sec, but it certainly looks like it).
The supposed "foam" from the water looks more like a constant repeating cloud mesh that might as well come from a machine.
In short: I think it looks like a white, flat rolling rug, instead of a rapid.
RDR, another open world console game, made rapids look like this, which I think is a lot better (yet still not perfect):
http://www.youtube.com/watch?v=_G_-a-L80eA&feature=player_detailpage#t=243s
http://www.youtube.com/watch?v=m5QTEs4IlEg&feature=player_detailpage#t=30s
http://www.youtube.com/watch?v=Gx5qbtE7LfM
That more looks like... you know, it's real actual water. Instead of a white, flat rolling rug.