I like it. But I think I'd like it more with a little more foreground ( or lower point of view).
[I'm a neophyte, so take my opinion as such.]
The colours and tones are nearly there. The blue in the sky is a bit out of balance, being too saturated for my eyes. You need to break images like this down into parts for better post-production. This can be done with ease in Lightroom, through the use of an ND Filter type effect, just for the sky. This would allow you to moderate the blues in the sky and have a separate control over the waters appearance too.
I'm not sure if you have a waterproof tripod, but if you do, you could try different POV's, such that you end up with all manner of images that concentrate upon certain parts and compositions of the old jetty posts. I'd be tempted to start off with concentrating on the birds and various placements, so they are above and then below the horizon line and using various positions of the tripod in conjunction with various reaches of your lens. It currently feels a little cramped, with the far stumps forming one lump of black.
I hope that makes sense?!
Thanks for the constructive feedback Oblomow and Alexander, always great to get such valued comments.. I was pretty limited with positioning I'm afraid: sat the camera on top of one of the stumps. Taking the tripod on vacation would be ideal but a lot of hassle (too mean to invest in a very lightweight job) but there were a number of times it would have been invaluable. I'll have a play with PP to look what to do with the colours in the sky. Thanks again guys.