I think Days is one of those songs that you have to be in a certain mindset to love it... And after it it will have a place in your heart or something.
Now I don't even know why I hated it in the first place. I remember thinking Ayu's singin was dragging and the melody reminded me of some christmas carol. xD But now I really adore the song. My thoughts of the song now: Ayu's vocal's are very clear and smooth, the melody is very simple but beautiful and the violins in the background are just perfect.
Oh and I also love the repeating piano melody (there's a better name for it but I can't remember) during instrumental parts.
But well yeah everyone can't like everything she releases.
I know because I'm
still in the minority that dislikes Curtain Call... xD Well, maybe someday....