The problems begin with the fact that the actor playing Breivik, Anders Danielsen Lie is significantly better-looking than his model, and in my view Lie's Breivik is also more 'together' than the real Breivik; he's less obviously whiney and pathetically video-games-obsessed just for a start. The upshot is that the film glamorizes Breivik. As for refuting B.'s monstrous ideology, the film-makers seem to believe that just (i) revealing that B. was & is a literal Nazi-sympathizer, e.g., by showing him doing Nazi salutes in court, and (ii) showing that B. ends up in indefinite solitary confinement (Note: B.'s actual sentence was, in accordance with Norwegian law, a little more complicated than that, but Greengrass's simplification strikes me as reasonable) and explicitly contrasting this outcome with his live victims' (esp. Viljar's) on-going, rich social milieus is counter-argument enough. But it really isn't. No kid who's tempted to think that Breivik and other extremists have a kind of 'red pill', and that they are on to some truths that mainstream society reflexively suppresses and evades, will watch 22 July and agree that Breivik was answered let alone comprehensively rebutted.
I dare say too that filming July 22 in Norway-accented English rather than using subtitles inadvertently builds the case for Breivik as a global figure, for the applicablility of his views everywhere.
In sum, July 22 is a kind of disaster. Greengrass didn't intend to do so but he's given poisonous ideology and hatred a worldwide, apparently innocuous platform. People of good will (i.e., for whom invoking Nazism is caution enough) won't see the problem, but for a small number of curious people with wavering wills, especially among the young, Jul 22 as it stands will be a gateway drug to worldwide White Supremacist thought. In my view, therefore, July 22 should always be accompanied by substantial refutation material. Bits of Racism - A History (2007) and The Nazis: A Warning from History (1997) would be a start, but a fully referenced, point by point refutation would have to be included somewhere. Netflix should use its recommendation algorithm to push such materials to viewers automatically, i.e., building on the model of supporting materials it used for Mark Harris's Five Came Back and also Welles's The Other Side of the Wind (to name just two tricky projects for which Netflix got considerable acclaim).
It gives me no joy to make this negative report. The acting and technicals of July 22 are all good to very good, but the inadequate and naive overall concept of Greengrass's film makes it bad and slightly dangerous given the world we actually live in, at least if July 22 is screened unaccompanied as it currently is. To be sure, July 22 is not extremely dangerous and potentially bannable the way an actual pro-evil-causes film, a true contemporary counterpart to Griffiths' and Riefenstahl's monsterpieces, would be. But the problems with July 22 are serious enough that changes in how it is presented are highly desirable and maybe mandatable.
[Update March 28, 2019: Some people believe that one shouldn't ever try to refute mad ideas, that 'to argue or explain is to lose', and that to answer (or diagnose or contextualize or...) vileness nonetheless gives vileness a platform. I disagree. While carefully considered refutations and diagnoses aren't for every audience, when vileness starts writing manifestos and poses as a rationally obligatory response to neutral facts about, say, demography and 'birth rates' then part of the communal response to that vileness must be to expose the spuriousness of its alleged rational challenge. We can't count on being able to talk paranoid true believers out of all their monstrous beliefs, but if we do our debunking job we can make it a lot harder for curious, new people to be gullible and slide supposedly rationally into believing utter nonsense.]