For whatever reason, this was released in the US before the UK, and so almost all of the published reviews at the time of writing are from American critics. This makes for fascinating, if somewhat exasperating, reading.
In general, they have a sympathy for the film's underlying politics, and that then affect their critical evaluation of the film qua cinema. More specifically, although a whole library could be filled with books about Americans' views on Ireland, what will suffice here is that it is a timely reminder that however well-intentioned, one will always see other cultures' problems through your own culture's lens.
The uneasiness in which US critics recognise (or ignore) the Palestinian flag in Kneecap is only one of the things that kept coming up in my reading. The newspapers' style guides requiring the capitalisation and use of term "Indigenous" when referring to the Irish language was also wryly amusing as well. Yet this last uneasily recalls the curious and clumsily-made assertion in the film that the band is the legitimate spiritual heirs of N.W.A., etc. Just like the Palestinian flag was only briefly glimpsed in the film, the connection to Black protest music is not repeated, with perhaps an eye to a US audience who might quibble with such a claim.
A few other critics suggest that the band are "a persistent thorn in the side of the British imperialist apparatus." This is, to say the least, something of an exaggeration. What they perhaps are a 'thorn' in the side of reactionary, clickbait media outlets that benefit from the controversy they generate. Many reviews also suggest that upon its UK release, Kneecap will unleash storms of controversy in (specifically) England. But I hazard that Brits hate the British police as well, and will actually dislike the film chiefly on account of its cartoonish and self-congratulatory depiction of the Troubles, not to mention the 'fan service' in-jokes about the Troubles… even if the viewer has broadly Republican sympathies. They will also, like me, likely take issue with the way that everything is tidily packaged for easy export abroad. It's not quite as cynical as the fraudulent counterculture of, say, Brewdog, and épater la bourgeoisie will always be fun to a certain extent. But there are diminishing returns to this kind of thing, especially when it is fairly evidently crafted for mass appeal.
Indeed, despite its surface brashness, there's a certain sense in which any sharp edges have been rounded off. The drugs they deal are both fun and recreational, with no substance abuse to be found. And then the film constantly tries to let itself off the hook by making justifiable political statements before equivocating with the likes of "but feck it, what do I know?". (I even spotted multiple uses of what I call 'Sundance squiggles': wavy, imitation hand-drawn lines that animate action.) One can't get over the feeling that the members of the group have already outgrown the rather juvenile, Sex Pistols revival—cum—Peaky Blinders swagger displayed here, and it's difficult for me to completely get on board with the notion of radio-friendly subversive beats... contra, say, drill or trap. Oh, and the hastily-dropped subplot about cross-border kink was a great shame. It's not exactly Hunger, is it?
As Kneecap’s rowdy goons find political purpose through their music and vice versa—DJ Próvaí finally, secretly, reaches his students through Kneecap’s songs—Peppiatt must deal with all the narrative padding he’s added to extend the film to its 105 minutes. There’s the dead-end romance, which starts as a punchline about political-difference-as-kink and goes nowhere from there. There’s the shut-in mom, abandoned by her husband and her movement after Fassbender’s character fakes his death. There are the endless endings, where Kneecap refuses to stop explaining itself, even when it’s showing us a seemingly climactic concert. Kneecap needs to keep the tempo up if we’re going to stay with its mad lads, but it too often overindulges on plot and finds itself frozen, couchlocked.
— Jacob Oller (AV Club)