He has a general book about the whole war, fairly short, quite good, but you probably won't learn much in there that you couldn't learn elsewhere reasonably well. (Take that with a grain of salt, by the way. I'm awful at recommending non-scholarly history books for casuals. That's probably an underestimate.) He's in the middle of writing a trilogy of massive books on the whole war. Book I was finished several years ago, and covers:
-the circumstances surrounding the outbreak of war going as far back in some form as the late 1880s, but with special emphasis on 1908-1914 and on the July Crisis
-the opinion of European citizenry about the act of going to war
-all fighting in 1914
-all fighting in Africa and the effects of fighting on the colonies
-all fighting in East Asia and the Pacific, the Japanese-US-Australian-UK quadrilateral, and the cruiser of Spee's squadron
-Germany's efforts at global war throughout the conflict
-the war in the North Sea to December 1915
-the process and methods of financing the war and of mobilizing industry to support it
-and "the mood of 1914" - the opinions of the European populace during the initial months of fighting
Books II and III are being delayed, unfortunately, due to his Oxford schedule.