The illustrations are awesome indeed; pretty much all big, iconic glamour shots reserved for important moments, and kind of a like a highlight reel from some bizarro alternate version of Berserk with Grunbeld as the main character. Weird, but cool, if not for...
And given that Miura is illustrating it, I find it hard to dismiss the idea that it is canon.

No. NO! I REFUSE TO ACCEPT IT!!

Hey, he helped with the animes and stuff, doesn't mean their changes are canon... this is an argument, right?
