I love it so, so much! I watched it last year because my friend told me it was about "gay guys in a band" so of course, I had to. There's a LOT more to it though.
I read the manga recently too, and I love the whole series even more! It's romantic with drama and obviously, has music-related themes, and everything about it is amazing. Even if you're not into the BL genre, I highly recommend it.