This film is somewhat similar to The Book of Life. They both are extremely stylized and use two (or more) different styles instead of using one coherent style. They both have very weak stories and bad out of place jokes. And they both don’t really represent their subject matter — a “celebration of the local culture”.
But The Book of Life has “friendship is magic” parts to its generic story and its design is “never seen before”. And The Secret of Kells is reminiscent of soviet animation tradition (considered to be surrealistic in the west), uses comics’ panels for no reason in couple of places and has jarring 3D in couple of others. Also the cinematography is somewhat stiff, probably to keep the age ratings, and sometimes uses a different art-styles, which are clashing with everything else.
The storyline is yet another “daddy issues” “hide vs expose” thing and i’m not sure if that structure is even related to the ireland or if it was just imposed by englishmen. “The waifu” which is heavily used to advertise this, is no more than a minor sidekick (with not that great voice-acting). And it has a lot of those. It has the whole “captain planet” team of racist stereotypes — literally “a big-ass ooga booga” (not even voiced by a black dude), a short, wise, ancient, long-living “the gook”, gloomy slave (what an orthodox can do in the Abbey? Was there schism already?) and a fat mumbling italian with mario stache doing fingers. And on top of all that we have the irish cat. The fairy is basically a plot device, team racist is no more than out of place “””comic”” relief” and the cat is perpendicular to everything. It exists only because it’s irish and they just had to namedrop it here. The now topical wall is only methaphorical — the evool vikings can just teleport on top of it. There is no proof or explanation of why it was a bad idea, and how everything would be better without it. And the vikings are just orks. Not different culture, not barbarians, not bandits, not even people, just orks. And even truly irish Cromm Crúaich is just another Níðhöggr\Jǫrmungandr going full οὐροβόρος. Isn’t this supposed to celebrate irish unique selling points?
Of course some types of catholicism can go full regional, like black gospel, modern “latino” gangsta catholicism or polish “angelic” hussars. But what is depicted here is so anglosphere-mainstream, that i know that it’s irish only because i read the wiki entry afterwards. I though it’s just some surrealism inspired by soviet-born Геннадий Тартаковский (especially considering the similarities between his Samurai Jack and ᴅʀᴀᴍᴀᴛɪᴄ scenes in this movie), put in the general western europe medieval-type drawings.
It’s peculiar, quaint and picturesque, but even The Book of Life has more going to it’s story and it’s characters. And for someone very familiar with soviet style of animation — this movies is not even that rare, notable or outstanding.
And there is no secret.