1)Power scaling was off the charts, and the protagonist who couldn't even move at first now is able to cut down tanks in half (0 training) and later is implied he could cut a planet too... too much for a serious fight!
2)Their powers were endless and confusing, transforming their limbs, regenerating, etc etc and without proper shading you couldn't tell apart the backgrounds from their bodies or what was really happening... chaotic.
3)The protagonist made a fatal mistake.... Starting off a fucking jerk too full of himself for someone who just got lucky, that doesn't work anymore, no matter how much one claim that "he gets better after a while" because this was the worst part of naruto too.
4) The heroine was boring, lame and weak
5) The protagonist was "The chosen one!!!!"
For me the worse part was the protagonist to be honest, 0 charisma ... Looks lame as fuck and starts as a jerk