Demons Souls, Dark Souls hype is nothing like Halo, Grand Theft Auto. If you havent played Demons Soul you really dont know or understand the pure awesomeness of the game. It's a game you either love or hate with a burning passion, and there will be alot of those who will buy it because they think they know what they getting into and rage quit 2 hours later.
The 95% of the game pain and suffering and some of the most frustrating situations you will ever encounter in a game.
However, it's about that 5% that is the most rewarding thing you ever encounter.
Also Demons Souls story and setting is not something simply good vs evil. It's probably one of the scariest, most grim, and dark games out there.