Alot could have been done differently..but there is no need for it to have been done differently. Its a wonderful photo. If it would be possible, it would be awesome to have had the light house on the right so we could see the swirl in the clouds. But its awesome the way it is.
I'd agree with Mark - Lighthouse on the right side of the frame, so that the silhouetted couple are facing into the composition, rather than out of it.