These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Game Breaker: Luca, a downloadable character introduced Trouble Witches NEO! has twice as much MP out of the entire cast as well as a significantly higher damage output than any other character in the game.
That One Boss: Lili. Unlike the previous bosses, she has a small weak-point that's only vulnerable for less than two seconds then closes her weak-spot off by some trap doors until it opens again. It doesn't help that Lily traps you inside her Eternal Engine form to restrict your mobility and she sends out spiked balls once her turrets and flamethrowers are taken out. Risking to go up close and personal to shoot her core during her first phase will likely get you killed (especially thanks to the standard Xbox 360 controller's cruddy Directional Pad and analog stick) as she moves around the closed off space. And it gets worse when she Turns Red because will fill the screen with bullets with little room to maneuver through them.
They Just Didn't Care: The entirety of Trouble Witches NEO's! English localization and humorous storylines gone horribly abridged is proof that Studio SiestA did not care for bringing any coherent story-telling into a danmaku shooter outside Japan.
Averted with some of the voice cast. You can tell some of them are trying, but for the most part, they still sound terrible. Whoever was behind the voice casting, however, clearly could not be bothered with finding people who could act.
What an Idiot: Symphony, full-stop. At the beginning of her story, she believed that her crown was stolen by one of Amalgam kids, but then she pulls out the crown from her pocket and places iton her head.