I can see that point. That section was indeed the hardest albeit that section's placement late in the game and the frequent saves you provide justify the difficulty. So, I would say it was more difficult, but not conceptually unfair, although I could see how some players might think that way.
Also, another note: I liked the one gem that you provide a peek of before the player falls down a chasm and then suddenly sees later in the ascent. That was clever.