That's a long running time and it's only the first half of a two-parter, with the second film being slightly longer. I'd suggest not thinking of these as films, but as a six-part TV series. Personally, though, I was fine. After watching 44 episodes of the anime, a mere 278 minutes is nothing. I'm well acquainted with Rei, Nikaidou, the Kawamotos and the others, so I was looking forward to getting reintroduced to them in a different medium.
Besides, the original isn't a plot-driven narrative. It's not completely without melodrama (a long-lost father, a marriage proposal, kidnapping (?) and THE BULLYING), but all that's in the trailer for Part 2. This first film has none of it. Instead it's a gentle, understated couple of hours in the company of a very quiet young man and his career as a professional shougi player. Films based on long-running manga often have pacing problems due to the quantity of story to be covered, but I hadn't been expecting such issues here and I was right.
Is it good? Yes. It's not gripping or thrilling, but it kept me watching happily enough for 138 minutes. Ryunosuke Kamiki does well as Rei. The character might seem to be a walking tree stump who doesn't react to anything, but we know there's more to him underneath and Kamiki always keeps us watching. That was probably the biggest danger with this film, incidentally. A flat performance in the lead role could have sunk it.
The rest of the cast's good too, though. Shouta Sometani made me laugh with his introduction as Nikaidou, while the Kawamoto sisters are thoroughly likeable. The most attention-grabbing role, though, is Kasumi Arimura as Rei's adopted sister, Kyouko. There's a lot of family in this film. We get an uncomfortably good look at what Rei's life was like with the Koudas, who took him in and in return for their kindness got smashed apart. (That's how Kyouko would describe it, anyway.) It occurred to me here that almost everyone in this series is an orphan. Here, that feels significant. There's Rei, of course, but also the Kawamoto sisters, Nikaidou and even Rei's adopted father, Masachika Kouda. (This film doesn't mention that, but he was.)
This isn't a plot-heavy film, but there's enough to support the running time. We're mostly following Rei's professional progress and getting to know his often grouchy, badly behaved or childish opponents. (He usually beats them, but not always.) The more important narrative journey, to be honest, is inside Rei as we explore his relations with people and the question of whether or not he even likes the game to which he's given his life.
It's one of the more successful live-action manga adaptations I've seen, actually. This is the kind of material the Japanese film industry understands. It's simple, understated and unhurried. It's complicated emotionally, being at once melancholic and hopeful. It can also be funny, e.g. the scene where Rei gets annoyed with Nikaidou's TV commentary and starts shouting at the screen. It has touching moments, e.g. Shimada's elderly fan club from his hometown. I'll be more than happy to continue with Part 2.