I enjoyed the film and the comic both quite a bit. I liked the conceit of having everyone appear in 'real time', according to when they appeared in the comics (well, OK, that might be stretching the point a bit in regards to the Losers, who appeared in later DC war comics, but you know what I mean). That turned out to be an interesting perspective from which to view things vis a vis the real world... seeing an evolution from the 'greatest generation' (the Big Three and the JSA) through the Cold War paranoia of the 50s through to the JLA and JFK's titular New Frontier.
Hal Jordan was a good choice to lead the story along, he (in his initial incarnation) being a contemporary of the Mercury Seven--kind of the closest analogue to what super-heroes would have been in that time and place, men who were first tested in the Korean War era and then went on to be Tom Wolfe's 'single combat warriors' in the space race. The Silver Age comics DC produced were singularly apolitical in that regard (compared to Marvel's Silver Age stuff, which was indelibly linked to the Cold War--which inspires me to mention the brilliance of Jon Favreau's decision to update Iron Man's earliest incarnation from the Cold War/Vietnam to the War On Terror, which worked really really well), though you have to imagine that the presence of a Justice League of America would have been a huge influence on the Cold War (at this point we start getting into Watchmen territory, though). At any event, it draws an interesting analogy.
I'll be frank, though, I think that the juxtaposition of JFK's speech with the iconic imagery of Flash, Green Lantern, Wonder Woman, Aquaman, and the Martian Manhunter facing off against a giant starfish was the most affecting moment for me--a great payoff to the story. Fanboyish as hell, but there it is.
--g