Beautiful animation and intriguing fantasy trappings can't save this anime from its so-so status due to its clunky pacing and undeveloped characters. It's a pity, too, because Gallego's original trio of books is, by all accounts, a richly realized world where the emotions of its characters are just as prominent as the magical occurrences around the characters, a distinct departure from most plot-driven fantasies with paper-thin characters. Unfortunately, in its anime adaptation, Gallego's characters have been flattened into types: Jack's the chosen one who has powers everyone knows about (but himself!), Kirtash is a bland hitman doing a job, Shail and Aslan are mentors who exist only to teach Jack. Victoria, who's just beginning to understand and use her own magical powers, is the most interesting and non-tropish character on the show, but we don't get a lot of time to know her between fight scenes.
Speaking of those, they are beautiful, as is the rest of The Idhun Chronicles. The animation in the scenes where our heroes spend time in a refuge for Idhunese expatriates is positively Miyazakian in its glowing beauty. The characters look great too: Jack and Victoria look younger than Kirtash, Shail, and Aslan, and each has a distinctive way of dressing that helps separate one from the other. The glimpses we get of the embattled Idhun are a wow too: multiple suns and moons in the sky; dragons that fly over otherworldly hills; hissing winged serpents. But without relatable characters to care about, it doesn't add up to anything great.