Alright. GET DEMON'S SOULS. If you have a PS3 and you don't get it, you're missing out on one of the best, most unconventional games on the platform. Assuming you have the time to play it, of course.
In my time playing Demon's Souls, I don't see it as very hard. Sure, I've probably died hundreds of times by now, but it's not like those deaths were frustrating. If you die in Demon's Souls, it's always your fault. The game isn't cheap, but it is unforgiving. The best way to stay alive is to just be careful about every move you make, keep your shield raised, and start out as a Magician because magic is much more effective against bosses you encounter early in the game.
Really, to get an idea of what all you can find in Demon's Souls, consult
this wiki. It details enemy types, items, weapons, and gameplay concepts and has a walkthrough of each area.