SHORT TAKE:
Wonder is a moving, funny, charming, honest and brilliantly constructed examination of the axiom: You can’t (accurately) judge a book by its cover.
LONG TAKE:
MILD SPOILERS
My husband and I have a shorthand way to refer to a cinematic experience. A good movie is a diverting entertainment. A good film is a piece of literature which makes you a better person for having seen it. Wonder falls into the latter category.
Wonder is based upon a book, also called Wonder, which was inspired by an unfortunate experience of the author, Raquel Jaramillo, writing under the pen name of R. J. Palacio. At an ice cream store with her own young child, they met a child with a severe facial deformity. Her toddler began to cry. Instead of engaging with the child with the facial disfigurement, as she later wished she had done, and show her own child there was nothing to be frightened of, emabarrassed, she instead removed her child from the store, only to realize later that she had effectively ostracized the other child. She "wondered" how she might have handled the situation better.
Wonder is the story which emerged – made up of an amalgam of experiences from real life – of a little boy named August "Auggie" Pullman (played brilliantly by Jacob Tremblay) born with severe facial deformities. He suffers from the genetic mutation known as mandibulofacial dystosis, also known as Treacher Collins Syndrome. Very rare, it results in underdeveloped facial bone structures – the symptoms range from almost undetectable to a face that is unrecognizable. Thankfully, it usually effects almost no other systems – intelligence, internal organs are usually fine. But the trauma for both child and parents in overcoming the challenges this disorder imposes is unimaginable in the more severe cases.
Homeschooled for most of his 11 years, as he and his family endured 27 surgeries just to allow him to hear and see normally, Nate and Isabelle Pullman, played respectaively by Julia (Pretty Woman) Roberts and 
Owen (the voice of Lightning McQueen from the Cars animated franchise and partner with Jackie Chan in the Shanghai movies) Wilson, Auggie's parents, decide to send him to a "regular" school to facilitate his adjustment to the broader outside world.
It is enormously refreshing to evaluate a movie where the parents are 
good, caring and kind people who love their kids and are still in love with each other. Julia Roberts plays Isabelle as a Mama Bear, protecting her cub and providing him with the security of her fierce unvarnished love. Owen Wilson’s Nate is funny, honest, affectionate and the heart of the family, whose unconditional acceptance and child like laid back approach to even the toughest of dilemmas gives Auggie a way to perceive the world with some of the sharper edges softened.
The teachers represented by Mr. Browne (Daveed Diggs) are unaffectedly quirky and portrayed as sincerely engaged with their students and genuinely interested in their students’ welfare and education. 
And the principal, Mr. Tushman, is a decent, reasonable, prudent man who moderates discipline and justice with understanding and kindness and is charmingly personified by by Mandy Patinkin ("Hello. My name is Inigo Montoya. You killed my father. Prepare to die." – Princess Bride).
Adults behave responsibly as they should and 
the kids in this story act like kids – shocked they stare and ignore Auggie at first and some are even unkind, but eventually Auggie’s courage and endurance and intelligence win many of them over and he learns what it is to earn and bestow friendship.
Their surname is most telling. These are people who PULL others towards them with their open and obvious genuine familial bond, their concern for others, and their strength.
As described the movie would have been delightful, but the writers have added a layer which raises a good movie to genuine cinematographic literature .
Just when you, the audence, believe you are familiar with the characters of the movie, there is an unsignalled change of focus. Right at the point when Auggie is confronting and learning to deal with his challenges we see many of the previous events from the point of view of 
Olivia "Via" Pullman, (Izabela Vidovic), Auggie’s older sister. 
Kind, affectionate, and ever-supportive of her hurting little brother, she understands and accepts intellectually that Auggie needs more but she feels neglected in what seems to be a secondary "also ran" position. She hides these feelings as well as her own social problems and 
even joys, believing her parents can not handle any more challenges or distractions.
Then we switch to Will, 
Auggie’s new best friend, who is seen from several points of view as he tries to peel himself from the "in" crowd which at first rejects Auggie and painfully grows to be a loyal genuine friend.
Then to Miranda, (Danielle Rose Russell), Via’s former best friend, who appears to have pulled away from her "adoptive" family over the previous vacation, but who is nursing pains of her own.
Meanwhile we get glimpses into the lives of others –
Nate Pullman, the Dad, (Owen Wilson) who seems to be the most chill member of the family – always with a gentle joke or turn of phrase to defuse a situation – but who absorbs the pain of the family because he sees the most.
Isabelle Pullman (Julia Roberts) whose fierce support and unabashed loved for her physically challenged son obscures her vision of her daughter who feels like an understudy in life.
Even the bully, 
Julian (Bryce Gheisar) who torments Auggie the entire movie, is eventually seen from an explanatory perspective.
And at some point, we as audience members, realize that we too, have been guilty of pigeon-holing and stereotyping the characters we have watched. No one in this movie is two dimensional or should be seen from a single angle. And we are the better for learning that lesson as we can apply that to those we come into contact.
Even Auggie, at last, must learn that despite the fact he APPEARS to have the most obvious challenges, does not make the obstacles others have to face less painful or daunting to them.
God gives us all obstacles to overcome and the strength with which to, appropriately, face them. Everyone misjudges, everyone misunderstands, even Auggie – which is OK if you learn from your mistakes. This is the lesson which Auggie, his friends and family learn from each other and teach us during the experience of this cinematic literature.
Isaiah 25:1 O LORD, You are my God; I will exalt You, I will give thanks to Your name; For You have worked WONDERS, plans formed long ago, with perfect faithfulness.
Jeremiah 1:5 Before I formed you in the womb, I knew you.