I've been listening to the single for a loooooot of time in a loop and totally enjoyed it.
Into the world: This is epic. Not epic in a Red Moon sense (?), but in a hopeful, joyful way. I think it could be a better ending to FotW album than FotW itself. I adore Far on the Water, but Into the World is just more powerful, moving. The last "iiiiiiiiiiiiinto the woooooorld" sounds heavenly ♥ I already listened to the live versions thousands of time before the single release, but today I was still amazed by how beautiful it is ♥
Marchen: Marchen was everything I was expecting and more. Marchen is a song from the Kalafina I do really love. First thing that came to my mind after finishing it was In every nothing and Tsuioku had a child. A precious child ♥ I loved the structure, and the flute and pretty much everything. Happens to me with this song the same thing that happens with Tsuioku, its melody is so catching that makes me to put it on repeat forever. 11/10 Perfection

And I want an instrumental as well! If I recall correctly, the Zaregoto edition of the single had it? I hope so
Haru wo Matsu: As someone already said, this is the perfect song perfect to listen before going to bed. It's calming, relaxing, nostalgic but hopeful. The piano melody is kinda simple, and even if there's no armonies, each of the girls voices shine by themselves. Wow, Keiko has such an versatile voice. At some points I couldn't believe it was her, she sounds so sweet. And Wakana, don't get me started on Wakana. This song made me remember why I love her so much

One of the biggest issues I had with her "new" voice is that sometimes seems so flat, not so emotional as before (I still love it, tho). But here is PERFECT, sounds much more lively, emotional, powerful, once again is the wakana that makes me cry

Specially on the second half of the song, it's GORGEOUS.
So, overall, while this single doesn't have anything really new or ground-breaking, was by far their best since KnGnN. For me it was like a comeback single. Having 3 totally different songs,representing all of their strenghts, felt like "hey, this is the very best Kalafina again! We still have so much to give! From now on, we'll be even better""
Ooops, sorry, I wrote more than I wanted, this single made me so happy I needed to sare my happiness

Also, when writing this I was listening to ItW intrumental and I'm about to cry. Please, please, if you didn't yet, give it a listen, it's GORGEOUS.
Kinda offtopic, but when I registered it took me a lot of time to finf out where the download links were "hidden". I saw everyone commenting "thanks for sharing" and I was like "but there's no link here" 