First off, welcome to Pixelation! I hope that you learn as much as I have
Here comes my crit...
Make sure that you aren't painting on a pure white background, use a darker color (40-60% luminosity with maybe a little blue or red if you're going for specific values). I think that's having a very negative effect on the contrast in this piece, or lack thereof. Your water shape even for something cartoony doesn't really make sense - the things sticking off are too long, and the shading makes it look like clay or something.
As for the ship itself, its very hard to tell what's going on. It appears to have the front on the right side, but the water makes it look like its moving backwards. The shading is not taking the actual vessel shape into account at all - it looks like one of those poofy embroidered things where all the shapes are sticking up the same amount. There are lots of things sticking off the ship, but only those 2 rear ones look like guns at all. The red markings are completely illegible, not sure what they are supposed to be. Overall, while I am able to discern at least probably the orientation of the ship, there is very little else that makes any sense. You have nonsensical shapes and boring colors.
The only thing I can recommend is checking out a few real battleships, and practicing some simpler structures so you can get a better grasp of your shapes and colors. That's not to say that this needs to be a realistic piece, but you need to know what you are trying to stylize before you attempt that. Good stylization is harder than realism; bad stylization is sloppy and cheap.
