As you can see from the four stars, I thoroughly enjoyed reading this book. (I first listened to it as an audiobook, actually. Daniel Passer does an excellent job narrating. ) Anyway, there are several reasons I liked this book.
First, i loved seeing the quasi-transformation Bobby underwent. As a somewhat sheltered ISTJ fourteen-year-old, I was at first put off by Bobby's relatively snarky behavior at the beginning of the novel. He is extremely sarcastic towards the beginning of the story. I typed him as an ISFP (FiSeNiTe), albeit a moderately "cold/intellectual" one. (Coincidentally, Harry Potter is also and ISFP.) Bobby is in no way the hippie artist that Tumblr uses to define the ISFP. I digress, but there is a point to emphasizing his type. His Te function comes out blatant and untempered at the beginning of the story, but toward the end he has learnt that there is a time and place for consideration of the feelings of others. Additionally, the relationship between Bobby and his parents CHANGES. It irritates me how the media generally portrays teenagers as rebellious and sarcastic parent-haters. I was disappointed that Clements apparently chose to do so at the beginning of Things Not Seen, but my disapproval turned to admiration as he skillfully turned the relationship in question around (without preaching!!!). I once knew a person who said, "If you start something crummy, it will BE crummy." I don't subscribe to that philosophy. Apparently, neither did Clements (I know it's not accurate to judge someone based on a single book, but just bear with me). In Chapter One, Bobby's relationship with his parents is indubitably "crummy." By the end of the book, one wishes to publicize the book to the point that it revolutionizes the teen fiction industry, all because of the positive message in Bobby's relationship with his parents.
Second, I found something intriguing about this book during my third or fourth reading. Clements gives no physical description of Bobby. None at all. Wait--actually there is a bit, but that which is present is scarcely enough to give the reader an idea of what Bobby actually looks like. For instance, we know that at the end of the book his hair is "longer." We know that he is "taller" than Alicia. We know that according to Alicia (who, mind you, is blind) he has a "nice smile." I like the vagueness of description in this book. If the reader was told that Bobby was 5'8", had green hair and brown eyes (or vice versa), and was any given ethnicity (one must be politically correct these days), the reader would be tempted to picture a person of that description during the story instead of an invisible person. Also, the lace of description strengthens the connection between Bobby and Alicia, who due to her blindness has no idea what he looks like.
Third, I was captivated by the intensity of the mental description. It was startlingly impressive. In Chapter Seven "First Night", Clements does a fantastic job capturing the essence of pure dread. Note to parents: If your child frightens easily, I would not recommend that you allow your child to read Chapter Seven (or listen to it--again, Daniel Passer reads almost too well). However, it is nowhere near as horror-filled as some of the other books in today's teen literature, which i call another bonus. At first glance, one would not call Bobby a highly emotional person (one reason i was reluctant to type him as a Fi-dom). It is there, though. Hidden behind his inferior Te bluntness is a bedrock of Fi sensitivity. Once i started paying attention to things other than his constant sarcasm, I was shocked at the intensity of his emotions.
Speaking of Bobby's emotions, there is one component of this book about which i am still attempting to form an opinion. This component is the relationship between Bobby and Alicia. It is developed more fully in Things that Are, which is told from Alicia's perspective. It is interesting to see the similarities between Alicia's and Bobby's thoughts. Their relationship starts out as an ordinary friendship, although from the start there is an undertone of "something more," i.e. a romantic relationship. Clements writes for the most part as though Bobby is the primary one who desires there to be some sort of romantic element. However, in the last chapter, Alicia sends Bobby an email which reveals much about Alicia's emotions concerning Bobby. Anyway, in comparison with the majority of teen literature, their relationship is pure and does not escalate too quickly. There is not much of the stereotypical "Oh, s/he is attractive, I shall therefore attempt physical romantic interaction with her/him." Bobby's knowledge of Alicia's physical beauty is present, but it is not the driving force of the relationship. And PRAISE THE LORD there is no love triangle in this book. Ninety-nine point nine per cent of those are unnecessary and detract from the plot. While the relationship between Bobby and Alicia is superior to most other teen romances i have read, I still have one slight qualm about it, that being that it is a teenage romantic relationship. Most (I only use "most" to avoid saying "all") teenage relationships are merely two persons acting on a mutual infatuation. I'm not certain i approve of Clements endorsing that (if indeed he is endorsing that). However, it was interesting to enter the brain of an infatuated person--I'm fairly certain that I've never undergone an infatuation, so now i have some idea of the thought process. On the whole I'm not entirely sure i approve of the message. However, as a "ship" it is far better done than, say, Percabeth. (And yes, fangirls, I did just go there.)
The other uncertain aspect of the story is that for a decent-sized portion of the book, Bobby walks around in public without clothing. This aspect of the book is the one thing that makes me hesitant to recommend it. I'm not fully certain what the moral implications of this are--is it right to do something wrong if no one will see you? However, the reason society imposes standards of modesty is because after the Fall it has become clear that for obvious reasons people must be to a certain extent covered up. Looking at the situation in this light, Bobby is fully "covered up" by his invisibility. He does not continue his habit of exiting the house unclothed after he can be seen again. Another way to look at this issue: if someone wore a full-body suit that caused invisibility and left the house in it, would there be any problem? Obviously not. The same principle applies here. In a way, Bobby behaved FAR more modestly than many teenage females today. I believe those who say Clements is endorsing public nudity have not thought their opinions through completely (or just used different logic). I could be wrong, but what i find to be reasonable logic points to the contrary.
All in all, Things Not Seen is a rather excellent book. I suggest that parents skim this book, particularly chapters 7, 9, and 28. Also, decide beforehand whether or not you want your child to read the two other books in this series, Things Hoped For and Things That Are. While the quality of writing in those books is on par with Things Not Seen, the subject matter is moderately more sketchy.