There are two kinds of people in the world: Those who watch the behind-the-scenes and making-of extras on DVDs, and those who don't. You probably need to be one of the former to pick up what Tolkien is laying down.
It's not as though the digital era originated the idea of getting to know the story behind a story, of course. Arts criticism has long been a place where people strive to understand a work by understanding its author, believing in the power of biographical information to unlock subtextual secrets. And then there is another school of thought, which can't help but find it frustratingly prosaic to discover that "she wrote about a car crash because her parents were in a car crash," or some such psychologically piercing nugget.
On one level, Tolkien is a fairly standard-issue artist biopic—and on another, it's constructed so tightly that it seems to point every moment in J.R.R. Tolkien's life toward the creation of Middle-earth. The story flashes back and forth between Tolkien (Nicholas Hoult) in the trenches of France during World War I and his childhood in England, where the young boy, known then as Ronald (Harry Gilby), is orphaned and sent by his Catholic priest guardian (Colm Meaney) to King Edward's prep school. There he meets his best friends—Geoffrey Bache Smith (Anthony Boyle), Robbie Gilson (Patrick Gibson) and Christopher Wiseman (Tom Glynn-Carney)—who together form the Tea Club and Barrovian Society, built around their shared desire to work in the arts. And in his boarding house, he meets Edith Bratt (Lily Collins), a fellow orphan with whom he falls in love.
Director Dome Karukoski and screenwriters David Gleeson and Stephen Beresford go easy on the framing sequence, which focuses on Tolkien trying to find Geoffrey near the front lines. The narrative otherwise remains fairly chronological, following the T.C.B.S. lads through their gently rebellious antics on the way to Oxford or Cambridge before the outbreak of the Great War and allowing time for the romance between Tolkien and Edith to blossom, impeded by the insistence of Tolkien's guardian that he focus on his studies. There are moments of authenticity in the interactions between these characters—most notably, an exchange between Geoffrey and Tolkien that feels a lot like the former's confession of being in love with his best friend—just enough to convey the bonds of friendship that will be so important to Tolkien later in his life.
The problem is that those bonds, like nearly everything else in Tolkien, feel mostly like a signpost on the way to the Shire and Mordor. We see young Ronald Tolkien and his brother being enchanted by stories of dragons, told by their soon-to-be-dead mother. We observe as Tolkien learns of Edith's infatuation with Wagner's Ring Cycle (which does include some A+ Peter Jackson shade when one of Tolkien's friends says, "It shouldn't take six hours to tell a story about a magic ring"). The scenes of carnage on the battlefields of the Somme include Tolkien's hallucinations of dragons, dark demons and other creatures. A sickened Tolkien even gets assistance during his dangerous quest through the trenches from a devoted soldier named Sam. By the time Tolkien reaches a scene where he explains with a dramatic pause that his impending fantasy saga will be about "... fellowship," it's hard not to want a break from the relentless literary foreshadowing.
It's understandable, and even generally desirable, for a screenplay to be efficient in its storytelling, whittling away everything that doesn't serve the primary narrative. But the primary narrative in Tolkien becomes entirely about the person J.R.R. Tolkien would one day be, leaving us too little room to invest emotional energy in the person he actually is during the time we're spending with him. Artist biopics of this kind are so concerned with "...and this is how he had the skill set to create the Elvish language" that they're unable to get an audience invested in much beyond historical footnotes. But, hey, if you're looking for a perfect DVD extra for The Fellowship of the Ring, you've come to the right place.