This game has a few problems. As mentioned so many times, those kings are tough to kill. In one of the later levels (Stage 2 Level 8) they might even fly around. Even bombs in their head don't guarantee a kill.
Like in Angry Birds, I would like the option to look at the things I'm shooting at before taking the (second) shot.
Some level difficulty misplacement – the last few levels (Stage 2 Level 10 & 12) were quite easy compared to lets say Stage 2 Level 8 and probably also some Stage 1 levels.