I really liked the concept and the visuals. Although i experienced quite a lot of bugs which led me to game over on level 2.
The first things was that by having world switch and arrow shooting on the same button, i completely missed the red key in the first level and it took a while for me to beat the level. There were some parts where i consecutively lost a lot of lives because of this mechanic, especially where there were angels and demons on the same spot.
There is some strange bug where i had a hard time jumping to the left from those tiny corners that stick out as if the input was being swallowed.
On the second level i had the most bugs. I was suddenly invincible, was able to walk on lava and walk through the locked doors. I didn't mind because i wanted to get past all the enemies and see how the levels were designed. Although i ultimately ran out of arrows and suddenly was mortal again. I had 3 lives left and they were quickly gone because i couldn't shoot anymore.
For my own gameplay, i didn't even notice the world balance bar and it didn't have any effect on the way that i played.
Hope this helps for fixing some of these things because i liked the appeal of the game.