Well, a short
(lolwut) analyze if I may:
First, compared to some of the latest songs released, it's clearly a comeback to definite parts song: intro (rythm guitar first, other instruments coming together, then vocals over), main rock riff using the main set of octaves, 1st verse (with a quiet lead guitar), pre-chorus, chorus (which as the pre-chorus does uses this main idea), back to a shorter intro, bridge, chorus, outro (which makes quite the originality of the song, going through to a climax). Thus, compared to Shinseiki for example, it's totally different, and makes it quite close to what they used to do during Sol-fa time.
As well, you can catch come similarities with other songs: intro makes me think of Aru Machi's intro, they're also using more and more an high pitch version of octaves riffs, which we've seen many times lately. I'm not sure yet with the radio rip omitting rythm guitar, but it seems Gotoh's playing full power chords at some points, which would be kind of new, and which they haven't done since Houkai's time. And as some have said, the road to the climax sure makes remember of Siren's climax, as well as Natsusemi's bridge to me with those high pitched octaves tremolo.
I think I've kind of figured out what's made their music change so much (though it hasn't so much in some many ways), and it resides in the way the lyrics are laid and sung. Gotoh seems to care not as much as he used to. I mean he seems to sing much more than before, but particularly through long phrases. Much less breaks, it's following the music as a whole, part by part, not the leading instrument (usually guitars) anymore... We kind of had that different way back in Shinseiki, though it's a rap-like effort. Of course the music has changed too, as some said the bass lines are much more detailed, the drums, while being clearly simple on some riffs, bring some fresh lines when it's needed, although apart from a few riffs, the lead guitar comes back to something pretty simple and repetitive, made with octaves, octaves and more octaves, and that quite a shame in my opinion, because guitars don't play the balance needed in some riffs where the bass and drums do in others... Which means to me that this pre-chorus (I'm quite happy they've come back to it, because that's like 50% of what make their songs so good!) and the climax end save the song in a way, as well as the vocals on the chorus, which are good for it, but sung to many times the same way throughout the whole song.

I was thinking mostly this. It does sound sol-fa-ish, which makes it seem like such a step back.
I appreciate that they had to fit it around the lyrics this time, and this song is more about writing a song from a new angle than making a staple of where they are as artists, but it still seems quite un-ambitious in it's structure.
There are nice touches which do a good job of distracting from that and it has such a nice energy to it. It matches the manga really well. A balance between vigour and emotion.
This song, to me, has nothing on shinseiki though.
I wonder if they'll include this on their new album. It would certainly make it feel a lot more open, like an extended version of MMAn.
As for the difference in his singing, I always got the impression that early on they used to put the focus on making rockier songs that built up the excitement to a crowd, whereas now they have the luxury of concentrating on the words and melody first. They don't need to be creating a buzz around themselves anymore.
His vocals in this song in particular are really strong though.

wow.. I love it!!! I agree, some lyrics do seem rush..but it seems like they are going back to some of their previous roots. This made my day, can't wait to see the pv!!!!

He didn't write the lyrics.