Now, I'll tell you this, from the reviews, I was a bit wary going into this book. Most of the reviews say something about how the language is strange and the "slang" is hard and so forth. But honestly, the cover looked amazing to me and I'm willing to try to get through a few language difficulties to get to a good story. And I had just purchased my Kindle, and it was only $10 or so - not a bad price!
First things first: people, get over yourselves. This book was not hard to read. Try reading the first part of The Sound and the Fury by William Faulkner and then come back to this book and tell me it's hard to read. If the "slang" is a problem, try reading A Clockwork Orange by Anthony Burgess and tell me THAT isn't confusing. Tell me Finnigans Wake by James Joyce isn't hard to read. I'm sure there are numerous other books to put here that have a rather challenging narrative. (And if you're asking, yes, I have read all of those books...or at least tried. Finnigans Wake was too much for me!) If the reason you pass this book is because of the reviews saying it was too hard to understand, don't. Yes, it's written in Matthew's point of view, and Matthew does have a very interesting point of view. But the way he tells the story isn't difficult to get through. When you read this, know that it's not all told to you upfront. Things will be explained. The book isn't written in usual prose, but it certainly wasn't enough to stop me from enjoy the story. Think of a ten-to-twelve year old telling a story (even though Matthew is around seventeen or eighteen, I believe). Comparing it to A Clockwork Orange, I mostly understood what Matthew would say in Above versus having to look up various bits of slang that Alex would pepper in his narrative in ACO because it sometimes would get to the point I would have to look up the word because I couldn't understand it in context. In Above, you do not need a glossary, you just need to pay attention to context clues. Matthew will usually explain what some items are as well, which helps.
It comes back to the fact that this is a fantastic story. This is a world where people are Sick, meaning anywhere to having giant crab claws for hands to being able to kill people with a touch. And the Sick people, they didn't like how they were treated Above - in the world we would recognize - so they escaped and made their own world, Safe. Matthew was born in Safe. Matthew also happens to be a Teller, which means he gathers the stories of the people of Safe and tells them, may it be through words or wood, since he happens to be a gifted carver. One day, Safe is in peril, and the inhabitants that aren't trapped below have to escape to Above and find out what happened and how to get their Safe back. This, of course, is a VERY simple explanation to a very intense, amazing story that I'm surprised doesn't have more reviews. It is a rich world with wonderful characters, most of which get fleshed out with an interesting backstory of how they found out they were Sick and ended up in Safe. (I personally didn't like Ariel for most of the book, but you eventually get her entire story, which makes rounds her out and made her more sympathetic in my eyes.) Remember what I said, how the story will fill it in? It does wrap all of its questions up relatively nicely. There's no gaping plot holes to get lost in that took me away from the book.
The story is told in a unique manner, but if you let yourself go a little and just read, you should be able to pick up on enough things that it shouldn't get frustrating and you should be able to enjoy it. Sometimes I didn't know what was meant by a certain word, but you figure it out. The story will give you clues. Yes, there are words made into proper nouns, but we as the reader have to understand it is because they are important words to Matthew. When everyday words are put into a proper status, it is because the author is making us take notice and think about them. Like I said, we are reading in Matthew's voice. Even though Matthew is almost an adult by our standards, you have to read it like a child wrote it. There's a sentence in the beginning chapter that reads, "I've told-asked-begged her to stop running." I loved how that read; it's a very childlike thing to say, but you can imagine what he means perfectly. If you are going to get so caught up in the way the story is told, then this book is not for you. It does lag a bit when the story goes Above, but the Doctor Marybeth character was certainly interesting enough to keep my interest. (The good doctor knew the characters who founded Safe from the hospital she interned at, and she was one of my favorites in the story.) Like I said, the parts concerned with Ariel lagged for me because I didn't prefer her character, but it wasn't enough to bog the story down for me. Then again, I'm one of those people who will skim the parts I don't like and then go back and read them. The world building was good enough in my eyes that I could see it in my mind, but the characters are what really pull this story together for me and make it shine.
My advice? Lose yourself in the story. Put aside your annoyances for reading something grammatically perfect and lose yourself in this book. It's worth it. Once I got into it, I couldn't put it down. This author has a wonderful gift and I'd ask you to take part in it. I can't wait to see what else she has to write.