Turtles All the Way Down, is somehow far darker, not so much because of the subject matter — though that’s dark too — but because of how he chooses to write about it. This novel is by far his most difficult to read. It’s also his most astonishing ... A sweet, conventional love story begins. But it hits a bittersweet, unconventional dead end. Aza can’t kiss Davis without panicking...But the real question is: How does such a story end for Aza? If an author has integrity, it should end plausibly. Green has integrity...I still wasn’t prepared for the ending of this novel. It’s so surprising and moving and true that I became completely unstrung, incapable of reading it to my husband without breaking down. One needn’t be suffering like Aza to identify with it. One need only be human. Everyone, at some point, knows what it’s like when the mind develops a mind of its own.

...like the best of young adult fiction, the book has a deep understanding of what it means to be a teenager ... This is by no means a perfect novel. The mystery and love story and mental health aspects often feel compartmentalised and it is 50 pages too long. Aza can be a repetitive narrator: this may be appropriate for someone who suffers repetitive thoughts, but can make the reading experience frustrating. Some of the recurring mental illness metaphors couldn’t have been hammered harder by Thor himself; it feels as though the illness-as-spiral idea occurs at least once a chapter, and there are more stargazy sentimental Big Moments than at a Coldplay concert. But all this is overridden by the fact that where the author is good, he is very, very good. In short, this novel confirms John Green as a great chronicler of teenage life. He captures the insecurities of youth in the way Judy Blume used to, and he ranks alongside such American masters of teen conversation as SE Hinton and John Hughes ... It will pluck the strings of those in tune with it. It will resonate with, and comfort, anxious young minds everywhere. It might just be a new modern classic.

In Turtles All the Way Down, Mr. Green shows the same writerly panache, but there is a bruised weariness in his principal characters that creates a more subdued experience for the reader ... This being a John Green book, the dialogue is snappy and sophisticated, and the characters invested with a sensibility, articulateness and aspirational range of reference that are so appealing to intelligent young readers ... Having wept through The Fault in Our Stars in both its book and movie versions, enthusiasts will want to know: Does Turtles All the Way Down offer the same sort of cathartic transport? It doesn’t, but perhaps it couldn’t. While there is tenderness and wisdom here, and a high quotient of big ideas, too, the stakes are lower, and so the drama is somewhat diminished ... There is arduous and unhappy turmoil aplenty in Turtles All the Way Down, but by the end readers ages 14 and older will find themselves, like Davis and Aza, in a place of hopeful ambiguity.

Turtles is a confectionary romantic comedy and a tear-jerker and a detective story and a high school friendship drama and a problem novel (the term used for young adult fiction illuminating a social issue like drug abuse or teen pregnancy). Its narrator may not actually be aware that she’s the imaginary creation of a man named John Green, but she knows all too well how a story has the power to hijack your life ... If Green’s fiction has a fault, it’s the way his characters’ thoughts and dialogue lean so hard toward the aphoristic, neat if melancholy formulations that seem purpose-built for excerption on a Goodreads favorite-quotes-from page ... Green created Aza, endowing her with his own wit, heart, and terrors, and perhaps in her dreams she appeals to him just as Molly pleaded with Joyce for escape. He told her story, but he never forgets that she is also telling his.

...superb ... Green, a master of deeply felt material, handles all of this with aplomb. With its attention to ideas and trademark introspection, it’s a challenging but richly rewarding read. It is also the most mature of Green’s work to date and deserving of all the accolades that are sure to come its way.

There’s romance, friendship, melancholy and no shortage of quirky charm in Turtles All the Way Down, so John Green’s latest young-adult effort falls squarely in his ultra-popular wheelhouse. Where the anticipated new novel differentiates itself, though, is as a thoughtful look at mental illness and a debilitating obsessive-compulsive disorder that doesn’t ask but makes you feel the constant struggles of its main character ... While Turtles doesn’t have the sharp tonal focus of previous Green books like the outstanding An Abundance of Katherines, it does boast clever one-liners, insightful witty dialogue and well-developed characters that are all hallmarks of the writer's enjoyable teen-dream prose.

The novel contains familiar pleasures — a scavenger-hunt like mystery that unfolds around a sweet-but-possibly doomed romance; clever banter; a binding friendship that only two oddballs can find with one another; and fascinating facts that become potent metaphors. In addition, he creates an arresting portrait of mental illness that could, earnestly, change lives. But the novel’s balance is off. While the portions of the book devoted to the lived experience of mental illness feel vibrant and vital, the surrounding John Greeny pleasures of plot and character are left underdeveloped ... Relating the tale from Aza’s point of view allows Green to show us how it feels to be at the mercy of unbidden thoughts...Green’s writing is uncomfortably, gut-clenchingly transporting ... Unfortunately, the book fails to depict anything else with equivalent depth. Sometimes it feels as if this is a byproduct of having a protagonist as obsessively self-reflective as Aza ... Green’s muddy plotting could easily be overlooked if Aza’s relationships were as vivid and believable as her illness. Sadly, all the characters other than Aza are underdeveloped.

Turtles All the Way Down (spoiler alert) doesn’t promise or offer much of a happy ending. Our heroes won’t find love, and there’s no suggestion that Aza will ever escape her anxiety disorder. Green is to be commended for keeping our eyes on the tough stuff … What bothers me about the story, however, is less what we are asked to focus on and more the distance Green maintains between his key themes … What is ultimately missing in Turtles All the Way Down is a clearer recognition of the proximity of the novel’s themes, particularly Aza’s phantasmal anxieties and the very real economic circumstances that at times peek around the corners … Turtles All the Way Down moves toward a mystified acceptance of things as they are — a move made all too clear in Green’s explanation of the book’s title.

Green’s signature whimsy pops up from time to time in his characters’ conversations, but his depiction of mental illness focuses on the sheer monotonous grind of it. It’s less a sweet love ballad than it is a scream ... Aza’s story feels real, and exhausting, and authentic. She does not get all the way better. The quirky cute boy does not save her. Her mental illness is not romantic; it is scary and boring, and sometimes it annoys her friends. What’s important is that she manages to make her way through life regardless ... Green’s observations do occasionally veer off into the kind of faux profundity that his detractors like to make fun of...But those moments aren’t so much cringe-inducing as they are endearing: They are straight from the earnest teenage heart of Turtles All the Way Down, which is feeling so very many things. And if it’s a little myopic in its focus — well, isn’t that another one of the universal bugs of adolescence?

Green's first novel since The Fault in Our Stars is another heartbreaker, full of intelligent questions. It's also a very writerly book, as Aza frames a lot of the questions she asks herself in literary terms. Am I a fiction? Who is in charge of my story? Why do we describe pain with the language of metaphor? Because of this, it's tempting to conflate Aza the character with her author, who has been open about his own mental illness. But readers need not know where the line is between the two to feel for someone trapped in an irrational, fear-driven spiral. In an age where troubling events happen almost weekly, this deeply empathetic novel about learning to live with demons and love one's imperfect self is timely and important.