The field of First World War fiction is by now very swollen, and any writer needs to bring something fresh to it. Barry's book is written through the perspective of his innocent and helpless protagonist, Willie Dunne, a working-class Irish volunteer, and does indeed recapture a powerful sense of horror. Two incidents - a hallucinatory first sight of a mustard gas attack, and Dunne's brief involvement in the Easter Rising - encapsulate the young soldier's bewilderment particularly strongly.
The book was reviewed by Laura Barber in the Observer, there is a useful Penguin study guide with an interview here, and Three Monkeys Online has another interview with the author here, in which he says :-
There have been so many books about other nations at the war, the English in the main obviously. But in Ireland I suspect the matter of the war became merely impersonal, after so long a silence, people not suspecting it had anything to do with them, especially as it hardly registers in any of our school history books. If it was forgotten for real reasons, both good and bad, it became forgotten for no reason at all. But it has been extraordinary to me the numbers of people at readings and in letters that suddenly realise they have this strong connection, and remember they had great uncles or whatever at the war, and are suddenly appalled by what they went through, and, in many cases, suddenly proud, suddenly amazed, suddenly thankful, which is wonderful. The forgetfulness was born out of self censorship perhaps.