Tomorrow When the War Began is a famous Australian book written by John Marsden* for a roughly teenage demographic. This much I knew before I watched the movie. The fact that it's the first of a series of seven I did not, and was thus shocked to reach the end at what I presumed was the middle.
I watched it because I knew it was a bit of a cultural icon in Australia, and I was vaguely curious, but not curious enough to read the book. Also I was given a choice between it or Casablanca, and, well, in hindsight I should have gone with Casablanca.
Initially I had assumed the "war" of the title was a metaphorical, coming-of-age/societal sort of "war." Nope, it was literal.
Now I still haven't read the book, so my comments are drawn entirely from the movie and the rest of what I can work out from wikipedia (not planning on reading the series, so was really rather curious what was to happen next), but all in all I thought it was a bit blunt. You could chalk it up to being a teen novel, but having spent considerable time in the Calvin College English department, I don't think that's much of an excuse for stereotypical characters, overt metaphors and a general clumsiness of content. I think a lot of that had to do with trying to cram three or so books into one movie, and the books are almost certainly better, but I didn't like the movie. It scared me.
It doesn't really take much to scare me (as probably anyone else who's seen the movie can now testify), but it came as one highly visual representation of a whole bunch of other real-life issues late at night one evening and the combined effect kept me up quite late.
The plot centers around a group of teenagers who've gone camping for a weekend and come back to find their families kidnapped and made prisoners of a real, literal war that's just broken out. I guess that was my major frustration with the plot in general: it just felt all too bizarre to be believable. If it were science fiction or something, sure. But this was meant to be taken reasonably real-life-like, from what I could tell. It just suspended reality a bit further than I was willing to.
From there on out, the teens wage a sort of guerrilla war against "the enemy" (unspecified) and ... keep fighting until the end of the movie, at which point nothing gets resolved in the slightest.
*Oops. To be perfectly honest, I thought they were written by Bryce Courtenay. Turns out he writes ... something else.