I read somewhere that this is a winter read and in New Zealand it’s currently winter. I honestly enjoyed this read .The dark element are dark not Disney dark and yet it’s littered with elements from fairytales.While a Fae Y/A book , I wouldn’t recommend it for fans of ACOTAR. They are on completely opposite sides of the fae/fantasy spectrum. The main focus  of relationships in this books is the brothers  not the periphal love interest. I also love that the illness journey was something they did as a team rather than leaving the brother to face it alone. 
I do think this is a book I would  have loved in middle grade. 
I really liked that the illness journey was something all the characters went on together instead of the one character needing to do it on their own.