I recently saw this on the big screen when the London Australian Film Society screened it on ANZAC Day and it really holds its own.
The script is wonderful - written by one of Australia's greatest playwrites, David Williamson. The acting is fabulous - I think this is Mel at his best and poor old Mark Lee, well he never really shook of this role to move on to others it's so powerfully iconic. The cinematography is gorgeous and say what you will regarding the rather jarring 80s synth theme - if you grew up with this film you can't imagine it with any other soundtrack. All pulled together by Peter Weir. Brilliant.
This is NOT a documentary in any way shape or form. If you want to learn about the Gallipoli campaign then I suggest you read a book about it. This is powerful storytelling with deep anti-war undertones. Tracking the journey of two under-age sprinters as they meet, con their way to signing up and travelling 1/2 way round the world in the search for adventure and find instead the shocking reality of war.