I kind of got a big fat spoiler for this movie by noticing that it's based on the short story "'—All You Zombies—'" by Robert A. Heinlein. I read that back in the early 60's; I still remember the Shocking Plot Device. So I expected the same thing here, and was not disappointed.
The protagonist, played by Ethan Hawke, is a time-travelling secret agent, trying to prevent a terrorist known as the "Fizzle Bomber" from blowing up a bunch of people in 1975. An initial attempt failed badly, leaving him seriously defaced (literally). He tries again, though. Along the way, he poses as a bartender, where he becomes acquainted with a younger person who entertains him with biographical stories, both lurid and heartbreaking.
Ethan Hawke always seems to look like he was just badly beaten up, and is about to get re-beaten soon. This role is no exception.
It's a very arty take on a story I remember as being as straightforward as a time-travel yarn can be. (I also remember it as being pretty filthy for an Omaha pre-teen, but what are you going to do?) But (ahem) unlike Starship Troopers, it's essentially faithful to its source material, and I think Heinlein would have approved. The movie's IMDB trivia page describes a number of fortune cookies in the movie for Heinlein fans. I'm ashamed to say I missed most of them.
Consumer note: as I type, the Blu-ray is cheaper than the DVD at Amazon. What's up with that?