Bottom line - a masterpiece is only a masterpiece because it's accessible and understandable on at least one level to the majority of people. This pretentious film will only be watchable to many people for its beautiful scenery and good acting which does not make it a classic. For instance, the basic story does not hold water. We are asked to believe that two totally different characters have a lifelong very close friendship which suddenly comes to an end as the older ( and supposedly more intelligent) character hits a late life crisis. He bemoans his lack of legacy having chosen to be single and childless and to remain on an island in the middle of nowhere. Thrown into the mix is gratuitous self mutilation which is distracting and unnecessarily graphic.
Any suggestion that the story about two warring men on the island is an allegory for the Irish Civil War simply doesn't wash. The Civil War was fundamentally based on indigenous Irish Catholics fighting imported English Protestants whereas both men in this story are Catholic and from the same little place, Inisherin.
It IS a sad film (spoiler alert - the little donkey dies) but basically you have to do all the work yourself to make any sense of the film and while that may be fun for all those self congratulatory folk out there who like to think they're "in on the joke" to the rest of us it just seems pretentious and patronising.