Dh asked his mates about COD for ds 14. They all said it was fine and their kids play it. (age 16 version)
Watching it, it doesn't seem gory per se, just the concept of killing people worries me for psychological reasons, but then ds does want to go into the forces anyway?
I do not mind stretching the age rating on some things but not sure about this one.
YABU - let him play it.
YANBU - he is still too young.