i like shadow pics a lot myself, but you need a subject in this photo. yea, it's pretty neat as it is, but it'll really me a SUPERB photo if there's a child playing on the beach or a dog running by, or something. see what i'm saying?
I agree with Molsen, nice "start" to a great shot. But it's missing something. Try messing with the saturation. Maybe to "over saturate" it may bring something to it (like the lower left-hand side).