Also worth mentioning that their +1 production per forest is a lot weaker than the Celtic forest/jungle-pantheon, which feels weird to me. Not exactly sure if one could claim that they are a straight up worse civ, but it sure feels like the Celts does their own specialty better than they do.Iroquois are maybe okay, but the amount of tiles they can work with decreases drastically as the game goes on, which detracts from the fun factor a lot.
At least Incas keep their Hills throughout the game.