I've found Crossbones to be a bit generic.
He works okay in the context of the storylines he's featured in, but he's always something of a plot device. Feels a bit "Bane/Talia" to me.
I would much rather see screentime given to a returning Red Skull and other classic villains.
Especially now that Bane has debuted on film, I think he'd come across a little less impressively.
Writer and Lyricist of GOTHAM'S KNIGHT: THE BATMAN MUSICAL
And if I'm right
The future's looking bright
A symbol in the skies at night