It caused quite a lot of debate here, particularly on the left as it dealt with the divisions wiithin the anti-fascist movement. Remember that as Stalin tightened his control over the Communist Party and the republic, he eliminated any who opposed him and who struggled for a pluralistic, truly leftist movement: trade unionists, anarchists, socialists and so on. The leader of the POUM, Andreu Nin was tortured and murdered by Stalin's agents.
So the film highlighted a nasty, less black and white struggle than that of the Republic versus Fascism, which hadn't been a theme of teh previous Spanish Civil war films. And reawakened the debate as to whether the Republic should have won the revolution first and then the war or the war first and then the revolution.
I was at the premiere with a group of Civil War verterans who had fought with the POUM and I remember Santiago Carrillo (a Communist) ungraciously storming out in protest. Afterwards we chatted to Ken Loach, a very sharp, interesting and agreeable man.
Whatever your take on the war, it's an important film. I'd recommend it wholeheartedly.
¡No pasarán!
And by the way, one of the actresses in the film is none other than Iciar Bollain, who has become one of Spain's most interesting film directors. (Te doy mis ojos/ Take my eyes)