The only reason why the games appear hard is that they basically created a new genre of games that, when approached like any other game, seems to be awkward and off-putting. But when you "get" it, and it doesn't take that long, you get it. Dying and trying things is a big part of the game, and at first it seems like deaths, and losing your experience points, is a massive loss. But really, it's not. You can basically finish those games without leveling once and by using a damn short sword from beginning to end, so levels are just a nice bonus to have. Experience points ("souls") are easy to come really. And despite what it seems like, you are never really that far away from the last checkpoint ("bonfires"). Once you realize this, it really frees the mind to just adventure without constantly quicksaving.
Online interaction is unique too. I mostly play the game in a way where I can't get invaded (undead form, or unembered, or whatever depending on which game), but you can still see ghosts of other people around, and there messages. Small touches in Dark Souls 1 were great, like how you could hear the bells when someone killed the gargoyles in THEIR game, or see bloodstains of people who have died in THEIR game, or their petrified statues when they got cursed.
The only thing that could be a bit clearer is how you develop your character. Weapon scaling and stats allocation are hard to grok.
But the gameplay itself is so deliberate and satisfying...
I love the world building too. Few games manage to have such a sense of place. And there is some narrative but you're free to dig into it... or not. You have to look around and look at your items to figure things out.
Dark Souls is just like... Hey, here's a place, a dark and low-fantasy place, have fun in it. No constant cut-scenes, no hand holding, no cheesy characters and predictable things. And a lot of items to fiddle with, character builds to try, etc.
I could go on, Dark Souls is amazing.