Great subject, some great color in there.
I find the ghostly rocks in the foreground to the left to be distracting -- if this is the effect you're going for, great, but as the previous commenter suggested you need more of it. It looks accidental, and like a mistake, now, and it doesn't really work with the rest of the image which seems to be going for straight photography, sharp and realistic rather than soft and ethereal.
There's also a light area in the sky upper right that feels a little weird.
The composition overall doesn't seem to have much punch. The "horizon" line bang in the middle of the frame feels.. weak? Bland?
The ridgeline, the "horizon" line and the rainbows are all leading the eye to the same place - strong. The edge of the water feels to me like it's leading up from the lower left to the upper right, contradicting the other lines. Since it's such a strong visual line, it leads the eye up and into the wrong place. I feel like there are several crops that would produce stronger compositions.
Overall, the contrast seems low. This is the kind of image where we're kind of expecting a little more visual pop - more saturated colors, more contrast (thanks, Galen), so I feel at any rate that it's a little less punchy than it could be. Of course, I wouldn't support pushing either of those levers very hard, just a hair more of each, I think, would help this out.
That's a lot of complaining, I know
There's a lot to love about this image as well, but you know that already so I won't waste a bunch of time enumerating all of that stuff.