As my favourite series, I have to talk about the good parts, as well as the meh ones. So, of course I'd do one for s2 as well, which improves on s1 in basically every aspect~

And don't you dare say "Oh but it's full CGI not watching/how could it be prettier" – I literally could not tell it was 3D first time I watched it and honestly still can't, except in certain circumstances.
And also... it's not like you could do much worse than s1's art/animation, putting aside the fact that SANZIGEN is basically one of two studios I'm aware of whose full CGI works are well-liked. This season is a bit choppy, looking back at it, but it really is a vast improvement on s1~

Music:
With Roselia finally doing some songs for this ~~I pretend the OVA doesn't exist~~ it's obvious the music quality goes up~
But it isn't even just Roselia's and Afterglow's songs that up the quality. Popipa has some far better songs this season, too – in fact two of my top three songs of theirs are from this season~ (I'll talk about this a bit later)

The quantity of inserts also goes up, to an honestly incredibly high level. While s1 failed drastically at quantity and slightly at quality, s2 has very high quantity and generally high quality~
When it comes to insert quality/quantity, you can't have too much of either, unless it sacrifices the other too much, which, as I've stated, this doesn't~

The openings are both really great. Kizuna Music is a really catchy and brilliant song, one of Popipa's best, and BRAVE JEWEL is Roselia. Only standard for Roselia, but nonetheless Roselia~

The endings though... Jumpin' is kinda... awful. And Safe and Sound... sigh as much as I like Roselia, their endings are among their worst songs for me. This is a better ending of theirs, but it's just an "alright" song...
Also on the inserts... PasuPare's are forgettable and Hello Happy plays perhaps the most techno song of the entire series in their focus episode...
But meh. Minor issues.

Characters:
I mentioned in my s1 review how there is often a problem in music anime, where there's a huge cast with little-to-no focus on 90% of them and how the small cast let s1 mostly avoid that.
Now, with a cast about six times the size of s1, some may expect it to fall into that problem...

But no. It doesn't~
Each of the four initial bands (obviously excluding Poppin'Party) gets an episode dedicated to them fairly early. So does the one lone character with lots of relevance.
And the other band that shows up... they don't really need the focus as far as this season is concerned, as only two of them are truly relevant. And they, well... get the focus they deserve.

Sure, the first episode is a bit sudden with introducing everyone and it can feel awkward, especially with how PoPiPa's members have seemingly developed some strong connections with these new characters off-screen. But it does introduce them well overall, through those aforementioned focus episodes.
Also it doesn't try to make them all super important or waste precious time having them all help out somewhere when they don't need to or anything like that.

I won't be going through the characters one-by-one like I usually do because that will take too long.
What's important, is that the characters get the right amount of focus. The ones who don't contribute much to the plot right now have one episode in case they're needed later. Those who are highly important get the necessary amount of development alongside the drama.

Story:
As I mentioned earlier, the first episode starts off awkwardly. And also, the focus episodes of the bands can feel kinda pointless, especially episodes 4 and 5... but I think "better to have and not need" applies here, right? It's best to develop the bands as soon as possible, in case they become relevant later and there's not enough time to properly introduce them again.

But the drama itself... yeah I mentioned in my s1 review music anime often seem to take half the season for drama. This season also follows that pattern.

The other band, that wasn't part of the initial five of the project, gets first referred to as a band in ep7. This stirs up the drama, as a plot thread alongside the cultural festival. Said cultural festival also being the first anniversary performance of Popipa.

Episodes 9 and 11 are full of emotions and the climax of the story this season~  The drama here is simple, but very powerful. In other words, it's really good~
It... actually falls under something which I claimed to be a favoured trope of mine in music anime, though I didn't actually think of this instance when I said that. Anyway, it is definitely a plot point that gives really good drama...~

The song that was written in ep11, at the climax of the drama and emotions, is also just one of Popipa's best songs~

Overall:
As I said in the synopsis, this is just much funnier and more emotional. I said s1 was only a fraction of what it could have been and s2 proves why. The music quality, animation quality, the plot, the comedy... it's all so much better in this season~

While there are couple tiny bits of badly timed comedy that drag down the drama a tiny bit, that barely makes a difference. It still strikes the right emotions only a couple seconds later. That's also still better than a bunch completely unfunny, though perhaps better timed, jokes, right?