I've been making my way through "The Myth of the Great War : A New Military History of World War I", which goes through a military history of the great war. The details are fairly astounding - it looks like the Allies spent the entire war in a parallel universe, convinced that their huge casualties were not so bad, because Germany was getting worse. In fact, as Niall Ferguson detailed in "The Pity of War", nothing of the sort was happening - and by 1917, both the BEF and the French army had ceased to have significant offensive capabilities - they had been bled out by follies like the Somme campaign and Nivelle's 1916 disasters. It's not a matter of cowardice in any way shape or form - based on the accounts I'm reading, the French and the British soldiers (not to mention the Canadians and Australians) fought bravely - it wasn't their fault that they were being led by fools.
If you take a look at the other side of the ledger, Germany (and Austria-Hungary) had knocked Russia, Serbia, Rumania, and Italy out of the war prior to the entry of the US - had the US not come in, it looks to me like the Germans would have turned West with a vengeance (witness the nearly successful 1918 spring/summer offensive) and taken the UK and France out.
Of course, there are issues with Mosier's (the first book above) narrative - he ascribes too many faults to the Allied powers, and too much brilliance to the Central powers. Even given that, it's a worthwhile book - combined with Ferguson's book, it's given me a fresh look at the mostly forgotten conflict that the pre-WWII generation called The Great War. By all means, read the book yourself, and draw your own conclusions. The more I read about that war, the more I realize that it is the central tragedy of the 20th century. Yes, WWII resulted in many things that were a whole lot worse - but WWII was one of the things set in motion by the endgame of WWI. You can look at the 1919 settlement talks and trace down many of the current issues in the middle east and the Balkans. Some wars have results that you can look back on later and be somewhat happy about. There's really nothing about WWI that looks that way.