The attack speed difference is massive though. Maces are the slowest weapons you can get, so the few thousand thorns you get from it doesn't make up for base 0.5 slower attack speed.
If you don't have anything else? Yes it's fine. But it doesn't compare to pig sticker, especially once you have higher thorns value as you gear up (and upgrade the thorns gem).
As for the block part: I'm currently close to capping without the 30% passive and just went with the 15% attack speed passive for punish (I suck at remembering their names). Don't know how much of an increase this 15% is though and how it stacks. Anyone got the numbers?