There's a great anecdote in there about how on their march back from Arlington Cemetery to the Mall, they passed by a convention of the Daughters of the American Revolution, who huffily commented that, "This isn't going to go over well with our troops," and one of the vets said, "Lady, we are the troops." So much for protestors not supporting the troops... Just in general, the film does an extraordinary job of showing how the current administration is trying to get the public to make the same mistakes now that it did then -- confusing the war with the warriors, or the nation with its leaders and current policies -- without ever needing to invoke any names or direct references to the present situation.
If nothing else, it's worth seeing it for the eloquence and moral clarity of Kerry's speech before the Senate Foreign Relations Committee, and his dissection of John O'Neal's nonsensical charge that Kerry was admitting to having committed war crimes (which I've heard echoed by too many people who ought to know better). I really do wonder what happened in the intervening period. I suppose in some ways getting older and having a more mature viewpoint makes life seem more complicated; and it may even be true that the issues of that day were simpler. But still, has he given a speech anywhere near that good, in the last twenty years? There are a lot of people who think Kerry fancies himself an heir to JFK. If he were still as persuasive as he was then, he'd have good reason.
Anyways, I don't think this is going to change anyone's mind who was planning to vote for Bush, but if you know any undecideds (do they really exist?) who dislike both, this might well be something that would convince them that Kerry is serious about public service, tries to make the right choices for his country, and is willing to put his own reputation on the line to fix things when he's been party to a bad decision.