I felt I had more problems with the knights BEFORE them. The hype behind Ornstein and Smough was just so ridiculous I expected the worst.
You're absolutely right.
Anor Londo is a mess for first-timers. The archers, obviously, will punish you relentlessly until you either bulldoze your way through them or seek help to strategize from afar. Tough customers in their own right, the Silver Knights inside have backstab windows much narrower than most enemies, and who can punish the player even for non-mistakes (e.g. -- landing a clean hit from behind instead of successfully performing a backstab).
Ornstein and Smough try to overwhelm the player with shock and awe. They want you to panic, to feel dread and despair. The moment you're overcome by that is the moment you lose, but not a second before. Staying calm and keeping to a gameplan is key.
yes, or blight town, the whole not sure where I could walk while being shot at by a toxic dart I can't see. But that's me saying what was the worst, but also that's where I learned backstabbing technique through being scared out of my mind.
But yeah, by the time you reach Ornstein and Smough you learn "Never fight 2 enemies at once." So it's really a fight about common sense. Actually the whole section before there's quite a lot of Invasion even if I'm looking for someone to help me, I'm just bait for someone to wack me while I'm at the bonfire.
But yeah, Dark Souls, boy scout level of preparation matters.