The book switches between the POVs of the four main characters; while this helps to gain insight into said characters, it also breaks the flow of the narration in the most irritating way -- which ultimately, is the book's greatest weakness.
I'm puzzled by how the novel handles mental illness, though it gets kudos for portraying depression somewhat realistically, I guess.
The ending was sweet; it operates off the serendipity effect where even socially awkward computer nerds are able to form meaningful connections and have improbably lovely, life changing moments. I think it's my own bitter, biased cynicism that stopped me from being wholly won over by such sentiment.
My expectations for YA books like this are set by Sarah Dessen and John Green. So while this book was a light, entertaining read, it ultimately falls short of said expectations.
(If I could, I'd give the book a 2.5 star rating, because I'm torn between "some parts I liked," and "eh, it was just okay.")