Personally, the games aren't that hard. I agree with Cody on them being overhyped. Honestly, I found Dark Souls easier than Demon's Souls, due to the refillable health potion whenever you rest at one of the fires. The only issue I had was playing in human form and forgetting to turn of my connection, since I encountered a few other players who liked to play dirty. But, in the game itself, every death is pretty fair, as you only die if you don't think before doing anything.
Also, I encountered a really weird glitch in the Painting world.
I killed the zombie dragon, and the front half of it disappeared, while the back half was stuck in the bridge. I couldn't move passed the stuck half of the body, but I could hit it with a power attack or any magic attack, and the legs would stand up instantly, as if it would continue fighting without the head, but instead it never moved after standing up, and I could walk through the legs and go on my way. It was a weird glitch