I think this is a Marmite book that most will love or hate, some will think it's a mixed bag.
I belong to the "mixed bag" group: I love Ruth Ware's books but this one my less favorite.
I liked the descriptions of Oxford and the last 15% of the book.
I wasn't a fan of Hannah, April or any other character. Hannah seemed a bit too spineless and repetitive, Aprile was a unbearable spoiled brat.
The plot is slow burning and some less pages would have made it more compact and exciting. There's a lot of repetition that seems to be there to recap what we already knew.
The last part is fast paced and exciting, the solution surprised me and I liked it.
3.5* upped to 4
Many thanks to the publisher and Netgalley for this ARC, all opinions are mine