Hardest level/part of the game?
I remember playing this when it first came out & the level "Truth & Reconciliation" was the hardest. Actually not the level itself but the point where you're beamed up onto the ship. I've beaten the game in legendary, but I was only able to get past this part with the help of a friend in Co-op play.
Now, I'm playing the remastered version and again, this part is the hardest, so far at least, I've got to get past it to continue playing the game! And I'm not even playing it on Legendary but rather Heroic this time around!