The ending ruined it and the Villagers were unquestionably evil
My mouth just dropped as she lied to protect the cannibals. Why??? To make sure Alijandro doesn't get rescued? What about the people that stumble in to the territory of those cannibals in the future? For that matter, as evil as Alijandro was, his evil pales beside that of the cannibals. By leaving Alijandro with those cannibals when she could easily have him rescued makes her 100 times worse!
An argument has been made that the villagers aren't evil because "this is their culture". I don't buy that. There are certain taboos that are so universal they show up in almost every culture and on every continent throughout recorded history. Cannibalism is one of them.
Also, I don't buy that the villagers thought these kids were the enemy. All the cannibal warriors were male as were any mercenaries they would have seen previously. By the standards of their own culture and what little they had seen elsewhere, there is no reason for the villagers to believe that the women were dangerous enemies.
I thought the film was quite good until that horrible ending. Roth did the dame thing in his Hostel movies where the protagonists turn evil at the end for no good reason what so ever.