Moving water is one of the hardest subjects to shoot in the landscape category, and that’s because of shutter speed.
On one hand, setting a faster shutter speed allows to “freeze” water, but the image looks somewhat artificial and harsh – at least to me.
Setting a slower shutter speed, on the other hand, can soften the photo, making for a more natural look, but of course some details are lost.
Finding the right balance can make or break a photo, in my opinion. I usually shoot in Shutter Speed Priority at around 1/2s to 1/5s, depending on the speed of the water. With these values I still get some details but the water looks a bit less violent.
One more thing to consider: when I’m presented an image with moving water, I’m instantly aware that it’s indeed a photograph, because in the real world you just cannot see water being frozen that way. It’s harder for me to really get into the photo, while that’s much easier with, say, a landscape with no moving subjects.
Even so, I really love shooting rivers and waterfalls: there are so many angles to look from, and so many details to discover!