Slayer - I gave up on it like a year ago as well. Then someone said, it REALLY starts after you beat level 1-1. And it's true. After you beat it, you then have all the other levels open to try, and there are some great levels, monsters and items. Still the game is haaaard. But it's funny, it feels like 1-1 is one of the hardest so far.
Kale - I see what you are saying. To me, it is a hardcore, no bullshit, difficult game, and brings me back to playing those old 2D adventure games, where they didn't hold your hand or give you save spots every 5 minutes. Also, the highs and sense of accomplishment I felt in Demon's Souls, are the best I can remember in years. I actually yelled out YES!, when finally beating a boss, or getting a bad ass weapon.
Dark Nemesis - Cool. yeah, it is pretty insane, though I like how you can REGAIN your soul, as well as see other player's messages or moments. I have had some pissed off moments in losing a major amount of souls. I just think the game is awesome how you can die on a stupid beginner level enemy, if you don't play smart. You can't just go into anything swinging and button mashng..very realistic. And I love all the animations for the different weapons.. really slick.