It is a good book — but I would caution that it was written in 1962. So excellent to read as a classic, but as representative of the latest research and thinking, not quite. And a lot has happened! Archives opened, Official secrets finally beyond their sell by dates, letters discovered in attics etc.
So much is spent on the progress of the "Great" war — especially the maudlin, poppies in muddy Flanders school of thought — and not enough spent on the hows and whys and wheres of what caused the world to convulse itself into its second Thirty Years' War…
If you would like to explore the area more, I wholeheartedly recommend:
Catastrophe: Europe Goes to War 1914, Max Hastings
The Sleepwalkers: How Europe Went to War in 1914, Christopher Clarke
The War that Ended Peace: How Europe abandoned peace for the First World War, Margaret Macmillan (A self confessed Tuchmann admirer)