To start things off I found an interesting article on the BBC a few months back that tried to debunk some of the most common myths about the Great War. I'm sure some of them can be cannon fodder for...debate.
http://www.bbc.com/news/magazine-25776836
1. It was the bloodiest war in history to that point. The 1850-1864 Taiping Rebellion in China killed more.
2. Most soldiers died. For British soldiers it was 11.5%, less than during the Crimean War.
3. Men lived in the trenches for years on end. More like 10 days a month and three in a row at the front line tops.
4. The upper class got off lightly. The death rate was 12% of soldiers, 17% of officers. Eton lost more than 1,000 former pupils - 20% of those who served.
5. 'Lions led by donkeys'. Over 200 generals killed, injured or captured and a unique type of war was won organizing a multinational force.
6. Gallipoli was fought by Australians and New Zealanders. British losses were higher than both Australian and NZ and the French lost more than the Australians.
7. Tactics on the Western Front remained unchanged despite repeated failure. There were significant equipment and tactical changes during the war, from planes to helmets.
8. No-one won. Germany surrendered before the country was crushed as it would be in WWII. It was still a loss to Germany.
9. The Versailles Treaty was extremely harsh. Germany was still the biggest and richest country in Europe and much of the reparations went unenforced. It was not as harsh as after WWII.
10. Everyone hated it. Those not on the front line often had better food, more money and more freedom than at home.