Thirteen Reasons Why is a book based on the suicide of one Hannah Baker. It revolves around the 13 reasons why she ended up committing suicide, the reasons which are made selectively public via tapes that she recorded before her death and ensured would get passed around to the 13 involved parties. 
 Characterisation 
 Well, it only says 13 people on the cover, but in reality you only get to know about 2. There's Hannah who you wouldn't connect to because there's nothing told of her that would ever enable such a feeling. From the beginning of the book she's just off rattling plot devices (aka the 12 of the 13 reasons) who've done nothing but anguish her (not really, they've all put her through such torment/minor inconveniences only once each). I use 'anguish' very lightly here. Even the narrator, Clay, couldn't convince me enough to like Hannah as a person. She just seemed to rise from her grave, so to speak, to put her tormentors on trial. Further, the very attitude of Hannah's (in actually sitting down recording the tapes, classifying the reasons into categories, making maps) speaks of clarity and doesn't make the suicidal side of hers very believable. It's tragic, but totally not believable. 
 The narrator, aka Clay Jensen, is equally bad. The narrator of a book is meant to be observant and paint an overall picture of the scenario because he is the reader's only input into things. If an author can't do this then the entire book fails. This here is a textbook example. Clay is so into his grief after Hannah's suicide and angry at himself over his inability to 'see the signs' and save her that it's turned into the only view he has on anything happening around him. This gets annoying real fast. 
 The remaining 'support' characters just appear to be plot devices, but nowhere to be seen as people. They're there for the sole purpose of furthering the decision of Hannah's suicide. They're so two-dimensional that I can't even recollect their names. They have nothing to offer to the book except being the catalyst that they are designed to be. There is no explanation for why they were being such jerks to Hannah. What Hannah describes is to be taken at face value, because why would a dying girl lie? Well, a dying girl might not lie but that still doesn't give me a whole picture. People aren't jerks for the heck of it, it's motivated by something and this is lost to the reader. 
 Liked 
 I found it novel in the idea of using tapes in place of a suicide note with tiny 'play' 'pause' and 'stop' buttons denoting what the narrator was doing with the tapes. It was also pretty neat to feature a double perspective on things happening - As Hannah speaks, the narrator reacts to it making it appear very natural with the listener reacting to whatever he's hearing. This however ended up getting pretty difficult when I was trying to speed-read the book because the difference was only in the way of font style (italics for Hannah, normal for the narrator) and I ended up confusing it pretty soon. 
 This book seems intended to be around one premise of how words can hurt others, how they snowball into something unimaginable and unintended - this tying in with the bullying Hannah faced. However, a lot of people who've rated it on a positive note seem to think that this book talks of depression and mental illnesses (because of the suicide involved). If we could remove that one misconception - this book does NOT talk of or deal with mental illnesses or depression - then I think it instantly turns into a slightly more acceptable book. 
 Didn't like 
 The first thing I noticed reading through was the acute lack of struggle, of showing that it was Hannah's last option to commit suicide. Reading through her reasons didn't convince me that suicide was the only way out (this here is very subjective, but my rational mind can't agree that she was forced to undergo anything suicide-provoking. It's a grey area, I know). The book, for me, seemed to say that whenever things don't seem to get better, suicide becomes a very rational option for people to take even if these problems are resolvable. 
 Personally I think that the reason this book exists is because she didn't bother trying. Now it might sound harsh but my question is this: who thinks of suicide as their first and only resort? Had she seen what could be worked out (like getting away from negative influences, telling her parents), or tried getting to know a few more peers a few of who would be willing to give her a chance despite her 'reputation', or tried indicating that she needed help, and despite all these attempts nothing in her life changed, then the decision to commit suicide seems sensible. 
 She also does not bother understanding what consequences her tapes would have on the ones left behind. It's as selfish as the act of her suicide itself is. This brings me to a related issue - Clay has done nothing to be named on the tapes. He's only named there because for the story to make complete sense (according to Hannah) he had to be named. So he's the golden egg amidst the rotten ones. The problem with this is that because of this, the book doesn't reflect on how the 'offenders' have changed their ways upon understanding the consequences to their actions (because our narrator never does anything wrong!). This, I find, would be a significant detail for the readers to know. 
 Finally, the very fact that all 13 of her reasons are put on the same level of blame is pretty infuriating. For instance, being molested and stalked is equated to having her poetry stolen and being slapped by a girl out of jealousy. Further, some of her reasons make no sense at all - one of which is that she was in a car with a drunk driver when the car knocks over a stop sign that leads to an accident later that ends up killing a person. Why this ends up being a reason for her suicide, I've no idea. 
 In the end 
 I would say that this book could have been so much more but ends with a lot being desired, On the other hand, this book has a great potential as a discussion starter (be it the reasons why, or the emotions Hannah must have felt or Clay's dealing with the aftermath of losing Hannah and so on) which is needed and should be the goal an author writing a book along these lines should aim for.