I like this game a lot! Cool pixel graphics, and a fun simple reaction dynamic. What would make the game AWESOME is if there was more variety added to it.
The current gameplay mechanics are fine, but what the game really needs to set it apart is more levels, a world map, more enemies, more items/weapons, bosses, and more songs. If this was accomplished, this game would be phenomenal!! As the game is now, it feels more like a "survival mode" rather then a full game. If there were a certain number of enemies needing to be defeated before moving on to the next level, the current gameplay mechanics would not need to change much, but it would feel like so much more!
Please update with more content, I purchased the coin doubler and all items IAP's for support, and I am giving the game a 5 star rating for now. I'm looking forward to future updates!