This being your first actual game, I'll go easier on you.
If you were to improve on the sound effects, and actually work on the art, this game would be decent. You have the mechanics well. The game itself is very limited right now though. If your not very good with artwork, then I would recommend you find someone else to do the artwork for you (since your good at programming, and I wouldn't mind helping out). Also, adding a storyline here would give this game meaning, and would truly improve the experience. Otherwise, this game will be lost in a sea of shoot em ups, since it does not stand out in the least. I'll be more than glad to help you out in anyway I can, from organizing a collab to helping you out with content.
Here on NG, its best to take a long time and submit quality work than too spend a little while on something that is the same as everything else, or dull and mundane.