It has potential
Though lacklustre in the realisation, this has potential. The graphics have a cartoonish charm, and I especially like the way the cannon does that cartoon standard squishy thing as it powers up to fire.
However, the enemy targets move far too quickly to make the cannon practical, and the scale of the playing field is far too narrow. It's an unrewarding game as it is presently, but with a bit of work, thought, and time put into, this could be a fun game, even if a Balloon Invasion clone.
Mediocre overall. Aspire to majesty.