Unconvincing cast
Something about modern war movies, the cast do not look the part of people from the early 20th century, but rather 21st century hipsters plucked into WW1.
Compare the cast to a film like Saving Private Ryan, where they picked actors that actually had a look to them that matched the era. When you look back at photographs of the soldiers, they all looked much older and more mature for their age, compared to the metrosexuals they chose for this film.