This is more gay YA genre fiction. The spoiler free tl;dr is that I read all three books in the trilogy in three days and enjoyed them it a bunch. The first book sells itself as part ghost story, part magical school, part chosen one narrative, and it's exactly that. I haven't read anything else by the author, but it appears the main characters, Simon and Baz, were originally part of a fake series that was the focus of her book Fangirl, which tracks, because the book has a paint by numbers sort of fandom vibe. Not in a bad way mind you. Sometimes I have a strong hankering for that AO3 OW mode and that's what this is. The plot is predictable but the characters are fun, and give me all the self-hating and fatalistic boys. Baz's miserable internal dialog was tailor made for my id.
The second two books break away from the more formulaic magical school stuff of the first, and I felt they were stronger for it in a narrative sense. The side characters also got more interesting and the adventure is more fun. The final ending of the trilogy was not super satisfying, but it wasn't major bummer either.