Okay, those expected an entirely historically accurate representation of the conflict will be disappointed. Although I'd question using movies to learn history in the first place...
As anyone who has read Ernie O'Malley's On Another Man's Wound and The Singing Flame, on which, I've been told, the film is (very broadly) based, or indeed who has any knowledge of the period, will know, half of the Irish Republican Army were not, in fact, a bunch of raving revolutionary Socialists. The politics of Ireland at the time have been crudely revised by Loach, on account of the director's own, leftish inclinations. Not that it isn't immensely enjoyable to watch Liam Cunningham, playing the trade unionist Dan, recite these words of James Connolly to cellmate Damien (Cillian Murphy):
"If you remove the English army tomorrow and hoist the green flag over Dublin Castle, unless you set about the organisation of the Socialist Republic your efforts would be in vain. England would still rule you. She would rule you through her capitalists, through her landlords, through her financiers, through the whole array of commercial and individualist institutions she has planted in this country and watered with the tears of our mothers and the blood of our martyrs."Not everyday you see that at the movies.
No, the main selling-point of the film - other than the sheer fun of watching something determined to upset the traditional version of history - is its concentration of the role of British imperialism in Ireland, and the way in which established institutions and the middle classes were exploited by the British Government to undermine and destroy any radical potential of the Irish nationalist movement. Ken Loach has also referred to the film's rather good timing, considering the devastation into which imperialism is plunging the world:
"I don’t need to spell it out, but the wars that we have seen, the occupations that we see throughout the world - people finally cannot turn away from that... Maybe if we start telling the truth about the past, we can start telling the truth about the present."In short, it's better than watching Snakes On A Plane.
On a final, somewhat humorous note, if you manage to get to watch it, look out for some of the Loach-isms, including: the IRA guerrillas politely warning some Irish police officers to stop their repressive activities, the 'baddies' having no women amongst them and all wearing uniforms (and the 'goodies' who sell out turning in their ragged clothes for some nice uniforms themselves), and the pro-Treaty officer who has a striking similarity to Joseph Goebbels.
See here and here for good reviews of the film.
To break the ties that bound us
But harder still to bear the shame
Of foreign chains around us.”