Most music anime have pop or pop-rock songs. Those are fine. Some have rock, that's amazing~
But basically none I've watched have had techno. Even where there was, it was few and far between. And techno, is the one genre I cannot stand. Alternative rock is fine, pop is usually fine. But techno is not.
And that's the reason I avoided this series for so long,  despite it being by the same company as Bandori.
It was bound to be full of technocrap.

A Bandori Youtuber I used to watch lots of videos by, also uploaded some D4DJ videos. I tried watching some of their D4DJ videos once... and realised "Oh the music's all technocrap." Seeing as it focuses on DJs, that was honestly unsurprising.
A bit over two years after that, I think, but before I started watching this, there were three original songs I could name. One is technocrap and the other two... are by the group which has an actual, proper guitar.
Before I started it, but on the very same day, I also heard a bunch more random ones from three different groups. Only one group defied my expectations and... for one, I'd never heard any of their songs before, two, I don't think they appear in s1, and three... it was still meh pop.

Anyway. So... was I wrong about it being full of technocrap? And does it make up for that?

Music:
I was not wrong.
Ep1 really didn't surpass my expectation, with the 100% technocrap opening, a repeated insert – which turned out to be the ending – which has some good parts but also some meh parts, and... a song I'd heard beforehand which was 100% technocrap.

As for the later inserts? For one, a lot of them are background ones...
The main group has only like half a dozen songs and... at first they surpassed my expectations by just being pop with light techno, nonetheless still slightly worse than meh... but some of their other songs were very much full on technocrap...

And the other two groups' songs are all 100% technocrap.

Story:
Okay now for one... why is this school so hyper-fixated on DJing? Like it doesn't seem to have any real reason to be, They mention the school gives a focus to the arts or something, but why does it seem to only be DJing that gets attention? Why are no, say, full-on idol groups mentioned as existing? Even just in the background that'd make a huge difference...
It's honestly the sort of hyper-fixation you'd expect from an anime made to basically advertise something...

Anyway. It's a... fairly solid start, introducing the other groups as people who exist from early on. But gosh the formation of the main group is slow. ~~I thought Bushiroad had learnt.~~ Ep5 also feels largely pointless, despite it being where the group is finally fully formed... ep6 also feels quite pointless.

And uhh... no drama until episode 8? Even then ep8's drama is pretty weak, 'cause it's far, far too clear what's going on. And the resolution for ep10 is easy predict, too.
It should be like ep6-7 at the latest... yet here it's in only a select few episodes after ep8.

Ep12 was the only actually emotional episode... even the finale wasn't that emotional, though that could just be tied to the music quality...

Characters:
Oh gosh freakin' hell I swear if I watch one more music anime with a super-hyper extroverted, bubbly and cheery main character – especially if they're an airhead – I will scream.
Rinku Aimoto, the main character, falls into the same pile of my hated characters as Kasumi. Oh how much I loathe that character archetype... plus airhead. Yeah I hate her.

Maho is... alright I guess? I really don't know what makes her unique... she feels primarily defined by how often she's seen in the bath or shower...

Muni is a somewhat arrogant, pouty tsundere, or something... she's a mix of funny and annoying moments.

Rei... she's fun~ Really cute and her shyness and her awkwardness at being a rich girl and shtuff– she's just fun~
My thoughts on her can't even be from any bias from her (former) VA because she doesn't even sound like the character I know her VA for most of the time – only really when she's singing.

The characters in the other groups... are even less developed. Peaky P-key's... I wanna centre, has no clearly-defined personality, much like Maho, same goes for the green-haired girl in Peaky. The other members of said group at least have a defining trait – one is apathetic and one is muscle-obsessed.

And Photon Maiden's members? Even though they get full-on focus episode in ep11, they have no clearly defined personalities, except the pink-haired girl seeing colours in songs.

Overall:
I genuinely don't get all praise it seems to receive and how much seems to be recommended, without even a warning of "first season is meh."
There's a high chance it gets better in the later seasons, sure... but out of all the multi-season music anime I have watched so far, this is without a doubt the worst first season.

With mostly boring characters and barely any drama, I'd honestly only recommend this to people who really like techno music...
But, like I say, there is a high chance the following entries are better...