I don't like them, they do low damage and the idea is to hit many times quickly to make up for it. That alone isnt a deal breaker, but if you mistime a parry, their blocking isn't good enough for high level enemy and you take a big hit, knockback or stun, etc. Where they shine is if you can get backstab hits, at 6x damage.
Anyway, I use them as a fun toy in the lower biomes, they are great for grey dwarf farming or bone farming etc. Plains and mistlands, though, no thanks.

A side effect of leveling these makes your unarmed fists much more useful.