an artistic point of view it is rewarding to show something different for the eye to see other than the “real” image. When it isn’t what the eye can see I regard it as art.
Living by the sea I take every opportunity to use long exposure photography to give the water a polished look.
By experimenting with your shutter speed you can achieve different looks to water, from a smoky look to a polished look with lovely reflections in between. To do this on a brighter day or anytime other than the magic hours of dusk or dawn, an ND filter might need to be used to enable you to slow down your shutter speed more. I use a 10 stop filter which I find very useful.
Experimenting is half the fun, take your time and have a go. I must admit I haven’t gone onto manual yet but I use the shutter speed (TV) dial and use live preview on my Canon 70D to see if it is right. Each second gives a different feel depending whether its the sea or a waterfall. With experimenting you will find out what suits you best. Also you need to consider the speed of the water beforehand as it can change what exposure you will need to use.
Below is a tutorial from Digital Photo school on reasons to get out and experiment with slow shutter speed. Good luck.