I just played back through CoO last week. While most of it was annoying, Panoptes is easily one of the most fun expansion bosses in the game. And the location is excellent. It feels like a raid boss fight. Personally, I think this should have been the strike. Tree of Probabilities and Garden World are bleh. I don't know why they avoided this one. That, or I wish they had had dungeons at the time and make him a dungeon. Imagine trying to reach him in the infinite forest, but he keeps changing everything and adjusting it, making it harder to reach him. He puts a Mind boss who keeps running subroutines on each branch of the forest until you can catch him and shut him down, then you have to fight through legions of vex to reach Panoptes. And then Osiris shows up and helps you and your fireteam beat him. Woulda made an awesome dungeon.