I got a chance to see this tonight with my wife. Let's open my opinion on this movie with two words....
If you genuinely like the man, if his ways and words speak to you, and you're not just supporting him because he's on your side of the culture war, you'll probably like this movie.
If not, you'll probably hate it.
Notice I say 'like' and 'hate'. I'd categorize this as a good movie, not a great one. Since this is most nearly a historical epic, I'm going to throw any concern of plot spoilers to the wind. The basic structural supports of the movie---who fought, why, who had the advantage of 'correlation of forces', and what was the outcome, are all readily available to you in history books and numerous websites.
Calles is called out, early in the movie, by Kellogg---he of the famous pact to outlaw war, and the US Secretary of State at the time, as a Bolshevik---that is, a communist. The US interest in the conflict is primarily economic---specifically, oil concessions for US oil companies. Needless to say neither the US nor the Vatican of the 1920s covers itself in glory here, greater or otherwise. Only under the present pope have the martyrs of the Cristeros war started to get beatified or canonized by Rome.
The portrayal of the horror show of Calles' minions is actually remarkably restrained, although still quite gruesome. The godfather and local mayor of one of the martyrs does his best impression of Pontius Pilate, and provides a great Obama campaign slogan for later this year when he invites the young Cristero to save his own life by saying: Death to Cristos Rey, Long Live the Federal Government.
I can just see that on a poster with a Warhol'ized Obama in the background. Perhaps some reactionary agents provocateur ought to have some posters printed to that effect on hand for Obama rallies?