I really like your photo! I wanted to do something similar with a lake we have here. There was a full moon the other night when I was out and I thought it would make such a beautiful picture with the lake and then the moon reflecting over the water..but of course I forgot my camera and by the time I got back home and got to the lake, the moon had risen up a bit into the sky and wasn't really effective anymore.
If the moon is the main and only subject then sharpness and details are the key focus. A blurred picture of a moon is usually not very appealing. Do a search for moon pictures posted on CS and read on the setup and techniques. Some use telescopes and some use telephoto lenses with tele-converters. I have seen very successful pictures from both methods. That should help you to improve in your future attempts. For a start, auto-focusing rarely works for moon photography and even if you use manual focusing, you have to take a large number of shots in a session, re-focusing for every shot, and then pick out the ones that are the sharpest before applying any further processing.
Yeah, that was the point, as the title suggests the inclusion of water, and he couldn't fit the water into the composition. I was overdramatic in the choice of "ultra", but 20-30secs exposure shouldn't be too bad right?