First is the style of music, it's the sort of high tempo electronic j-pop that just keeps the energy high. What makes this special is that the girls power up by singing, which means they sing while fighting, and most of the sound track is the same including the op and ed, which makes watching any episode like jamming to music, with the bonus that cool shit is happening at the same time.
Second is the cool transformations, special attacks, and just in general non stop action. All of the character designs look super cool, and because there are random Noise (sort of alien like creatures) out breaks almost every episode you constantly get to see Tsubasa summoning giant swords, Chris summoning thousands of rockets (MEGADEATH PARTY is a pretty sweet name for an attack too), and Hibiki just punching shit.
Third is in the down time it's a super heartfelt cute girls friendship show with Hibiki having a very strong relationship with her best friend Miku, and a good development between Hibiki and Tsubasa, and later Chris. There are lots of sweet moments with Hibiki and Miku sleeping in the same bunk in their dorm, Miku being upset that Hibiki hid her powers from her, and Miku encouraging Hibiki giving her strength to win some fights later on.
Really any of those elements by themselves are nothing special but the way this show combines all of them, and all the sheer tempo of the show with the non stop action really syncs with the soundtrack and watching this was like a flow state just zoned in having a great time.
As far as negatives the plot was pretty stereotypical, but not offensive, the animation towards the middle of the show was lower quality (but the first episode was outstanding), so what could make this show better would mostly be just more consistent animation. The plot is really a side note because it almost doesn't matter for the enjoyment I'm getting out of this show, and as I said it wasn't necessarily bad or offensive.
If you watch the first episode and think "this it sweet" and are just zoned in head bobbing to the music, then you will likely love the show; if you feel sort of iffy and looking for more after the first episode this show is likely not for you is my guess.
