Nice expansion to the original game. Original Munckin was brutally hard to win, requiring clever cardplay and backstabbing to even have a shot at winning. Unnatural Axe dilutes those cards so that the third or fourth person to go for the win should succeed.
Caution: The more expansions you add, the more the screwage is diluted, until it's almost just a race to level 10 vs the 1-2 undefendable blocking cards. If you add two expansions, death becomes rarer, and the game is more lottery and less clever.