Regarding the difficulty: I think Demon's Souls is actually a lot like Super Meat Boy, in that once you've put some time into the game and go back to play the first few levels, you think, "Wow, I actually found these levels challenging?" The game really rewards you for actually playing your character and for thinking about fighting as you might think about fighting: you can't just button mash/hack and slash your way to victory in Demon's Souls as you might in Oblivion, for example. You have to dodge; you have to use your shield; you have to know when not to use your shield; you have to think about your surroundings; you have to be conscious of your stamina; you have to adapt to situations; you have to be aware; you have to consider your stamina; you have to consider your weapon selection, and you have to consider the kinds of attacks each weapon can do.
Demon's Souls is a hard game if you come into the game thinking it's going to be like Assassin's Creed: Brotherhood, where you stab through 15 guys with a single, repetitive button push. Once you learn the game, its mechanics, and think about your class's progression, it becomes a decently challenging, but not overly hard game.
When I go back to world 1 now, I pretty much walk through it. I'm in my third playthrough now, and I haven't died a single time, because you really become adapted to the game.
There's some trial and error in there, sure. But there's also a lot of strategy. It's such a refreshing RPG combat experience: a game that doesn't assume you're an idiot and doesn't hold your hand, which so many games do now. Play the game, bottom line.