The game doesn't provide very much choice in the game play. It's like connect the dots; there's only one way to do it, no strategy involved, just systematically reacting as the game prompts you with things to do. This comes from the mechanic of pointing and shooting; you either hit them or don't, there's no middle ground where you can improve as a player.
One solution a lot of people use for this problem is to introduce an extra complication to the game the player has to consider as well; maybe it controls in a weird and interesting way (angry birds is shooting, except with gravity), or you need to consider some kind of resource (like how Dark Soul has a stamina bar which limits your actions, forcing you to think strategically). The game then becomes the interplay between what the player wants to do while taking into account, and eventually mastering, whatever it is that's preventing them from doing it. Much more interesting than a systematic or reflexes based challenge, because it forces you to develop compensating, multi faceted strategies in your head.
Other than that, the graphics were pretty good, I thought. Maybe the weird shape shifting asteroids didn't make sense, but they looked kind of cool. The music doesn't loop quite right, like a needle skip on a record (too old reference?). The user interface was pretty basic, but served it's purpose well. Overall, the production was pretty good.

why do you just straightup end the game.. ? why not let us continue upgrading?

Yeaaah...okay! It was ...too short. Well choice of music, the upgrade should glow when it is possible. Neat little game, I wanna play MORE!