The source material is six volumes long; a fine length to adapt into a film, and for the most part the pacing is handled with care. King of Thorn sees a colourful cast of cryogenically frozen characters awaken to a future ravaged by monsters. The introduction is well executed; it grabs your attention and gets you wondering. As the film progresses, it becomes rather typical of the survival horror genre, but the film exhibits a certain freshness as it isn't a genre often tackled in anime. Despite certain predictable elements, it's an enjoyable venture away from the norm. The film can't keep up the momentum, however, and the plot drops in quality nearing it's final act; it becomes more tedious than exciting as the story treads mind-boggling territory. Ultimately, the plot evens out as fairly average despite a promising opening.
The animation and art is reasonably well done, but certain aspects let it down. The backgrounds and characters are drawn in a traditional anime style, but the monsters are computer generated and don't blend particularly well with the surroundings. The detail is certainly there, the monsters themselves look the part, but attempting to blend two different art styles is often going to yield fruitless results. It's something you get used to as the film progresses, but ultimately it's something that could have been handled better. The more traditionally animated elements are wonderful, however. The visuals are crisp and clear, the Scottish scenery looks beautiful and the action is well drawn and choreographed.
The sound and music is probably one of the stand-out aspects of King of Thorn. The music is used appropriately and is generally impressive, as are the sounds of the monsters; sound editing is an especially crucial aspect in a survival horror, and is utilised well in King of Thorn. The music - or lack thereof at times - builds great tension and helps create an eerie, isolated atmosphere. The more upbeat tracks used during the action segments add a sufficient amount of drama and excitement.
The characters - given the runtime - are fairly well developed, minus a few who are there to up the kill count; such is the nature of a survival horror. The leading lady, Kasumi, does at times come across as a little irritating and certain character motivations and actions are a little puzzling. The characters are an adequate aspect of the film, but they fail to defy convention and never leave their moulds. At times they feel unfortunately underutilised.
Up until the final act, King of Thorn is an enjoyable watch, with a couple of picky elements here and there. The survival horror aspect is a welcomed change from most anime productions, but the ending is very hit-or-miss. There is merit in there - certain redeeming factors - but overall King of Thorn comes across as an enjoyable, albeit satisfactory film.
