I originally read Thirteen Reasons Why when it was first released and it has stuck with me ever since. For reasons (pun unintended) unknown, I no longer have my copy so when I spotted a cheap copy in a charity shop I grabbed it immediately and finished it the same day.
Hannah is a very damaged, fragile character who is disillusioned about the world she's in and the people she sees every day. You have to remember that a high schooler's mental health is much worse than those in a psychiatric facility and there is so much going on that you can quickly become overwhelmed, even by the little things. As Hannah said, for her this had a snowball effect and lead to her being more and more depressed before eventually committing suicide.
Clay is Hannah's opposite in many ways - he's the good guy. The guy that doesn't go to parties because he's at home studying. The guy that's in love with Hannah. One thing I particularly enjoyed about this book was Clay's grief, at the start he'd clearly not grieved for Hannah and we followed him as he went through the motions, listening to the girl he loved tell her story.
The only problem I had with this book was the way it was written, kind of. Hannah's sections are in italics and Clay's in normal type but my brain did get confused about who was talking at times, the same as when I first read it. I was forced to keep pulling myself out of the story so I could recognise who was talking.
I think this book is an amazing look at how people are affected by one person's suicide, and how kids in high school can be. It's a very volatile environment and one I'm particularly glad to have got myself out of. It's on my list of contemporary you must read, which is entirely in my head.