I like the feeling and mood creatied by the colours alot.
You've been able to keep the contrast in the sky relatively safe considering the range of light you were dealing with...great use of the flash.
A couple of nit picky things I would change to ented into a competition where EVERYTHING will be looked at: (I've never entered a competition, so ont sure what they are looking for). But from a personal perspective...
I wish the bride was just slightly angled a bit more to the camera, to see her profile.
There is an island to the right of the groom that is distracting.
I'm not quite sure about the grooms left arm, the space between his arm and body is unsettling? Maybe make it bigger of get rid of it...
Finally, the shadow cast by the flash behind the couple acts like a great diagnal leading line to mirror the shoreline, but it isn't quite straight...there is a bump just to the left of the bride either from grooms hand or uneven ground...I would maybe strighten that out...
Just my 2 cents, and it may not count for anything, but since you've had a lack of replies, I thought I'd get things going...=p