i honestly don't know if i can write a review right away but wow! i loved this book! it just kinda featured all my favourite tropes. it was my second audiobook ever and i was still not sure if i could trust it not to hinder my book experience but i fucking loved this book!
TLDR i love me some gay wizard romance with a hint of mystery and saving the world (but mostly the gay magical romance lets be real)

of course, you can't help to draw comparisons to the harry potter books - you can compare it with any other chosen one narrative, but both Carry On and Harry Potter treat the same way and in similar universes, so it ends up being closer. i think thats interesting, it didnt really take me out of the story much (i always get lost in thought reading any book that im enjoying) or ruined it.
now, i do like fantasy and mystery and all those genres as much as the next person, but honestly what really got me here was The Romance! i fucking love enemies to lovers! it's my jam! (or my butter, considering simon's disgusting snacking habit...). and #OMGtheywereroommates! i also enjoyed the use of queer. i know its a debated word, but i'm all for reclaiming it, and hearing it in a fantasy, non-homophobic context kinda gave me life. on the other hand, i wouldn't have minded for the word bisexual or pansexual to have come up at some point when they discuss simon's sexuality. it seems odd to not even offer that possibility. They do live in 2016 and have access to the internet, like c'mon. i'm not saying that he is can't be gay because he dated agatha, but there is are many possibilities outside the gay/straight dichotomy and it just felt a bit like a case of erasure
i really loved all the characters, i thought they were well built, i got their motivations, and it made the finale really make a lot of sense. furthermore, they are all a lot more grey, which is something that you never really get from harry potter. and i quite like that, not really knowing what to feel about this magical world and the people who more or less control it. in that sense it comes much closer to (lets say) the world of A Song of Ice And Fire.
I really enjoyed how things clicked into place, between the past and the future. even if to the characters not everything got properly explained and the mystery didn't really got fully solved except for the reader. i really hope simon gets to talk with lucy or somehow get to know the story, but i dont know if lucy will still be there in the veil 20 years in the future
the magic also made a lot of sense, which i find is not always the case in all books (im still so confused with it in the ASOIAF series), and i quite like to know how things work.
since it was an audiobook, i dont know how much i can judge writing; i did like the narration.