Another 10 RHD monster, undead this time. That doesn't bode well...
Boneclaws are large-sized, with reasonably decent ability scores (though the lack of any outstanding ability is somewhat problematic).
They have DR 5/bludgeoning, +2 turn resistance, a few points of natural armor, and a reasonable speed, as well as cold immunity: nothing you wouldn't expect from an intelligent skeletal undead. Unholy Toughness (charisma to HP) is also very nice to have.
More notable is a boneclaw's ability to extend its boney claws, giving it two natural weapons with the damage of Large shortswords and a reach of 20 ft. Given that Combat Reflexes is a thing and the boneclaw has a racial +8 dexterity bonus, this is actually a pretty nice ability.
However, for all that goodness the boneclaw has a number of major flaws. Its RHD are atrociously bad, and make it in fact incapable of getting a third iterative pre-epic. This assumes it can wield weapons at all, which could be difficult with claws that are half a meter in size (and sometimes more). Furthermore, its main selling point (20 ft. reach) isn't exclusive to it: any Large creature that can wield a guisarme is capable of replicating it.
Considering this all, I think -0 is an appropriate assignment here. Do discuss.