Dark Souls is just more Demon's Souls, except for people who've played Demon's Souls it is probably a lot easier. That was my experience. I found Dark Souls easier than Demon's Souls, but I chalked it up to knowing the combat already and being comfortable with the type of game I was playing.

So I'm a little confused if you liked Demon's Souls what made Dark Souls not? A couple systems got changes, but it is largely the same game.