Absolutely incredible image! Beautiful. I tend to agree with the whole lessening the color in the water, but that's really picking at an amazing shot. When you get this type of fantasmagorical pic, it comes down to such tiny details and personal preferences. Stand tall and proud - I know I would!
Let me begin by congratulating you on your red ribbon, very well done.
You have chosen a tremendous vantage point and waited for an interesting sky to add impact to your image. Your composition is faultless, the range of tones complete and the landscape fascinatingly interesting.
I can understand why the waterfall is the colour it is, absorbing light as it does from the sunset but I do agree with one of the rare questioning comments that its colour is a little off-putting. Although its in the interests of the natural light to accurately reflect what you see before you I might have been tempted to keep it but to reduce its effect. I would probably have also given it a shorter exposure to bring some detail back into the waterfall. I do love the base of the waterfall and the rich blacks of the water fringed with the icy sprayed surrounding grasses.
There's not a lot else I would have done differently here. I know from own experience what fascinating colours there are in the natural landscape of Iceland, I would dearly love to return in the very near future, it would be great to meet up.
Oh my heart longs for Iceland - a wanderlust provoking capture.
Is it Seljalandsfoss?
Did you change the color temperature for the orange in the water?