The Boy in the Striped Pyjamas by John Boyne

This is our book group selection for January.
I found the writing style of this book very powerful, the simplicity of the prose and the element of childlike lack of understanding about the events that were unfolding added to the horror felt by the reader. Bruno does not understand why the Fury came to dinner, or why his family had to leave their comfortable Berlin home to move to Out-With, or why none of the people in striped pyjamas who live don the other side of the fence were ever invited to dinner. His new friend wears striped pyjamas and does not understand why he had to leave his home above his father's watchmaker's shop to live in a single room with another family, then travel to the place he now lives. What both boys do understand is friendship, which binds them together to the end.
I found the book more touching than the film based upon it, but I can't decide whether the reader / viewer needs to see the horror and brutality contained in the story. Should it be explicit or implicit? I really don't know the answer to this.