Demon's souls is one of the ps3 best games IMO
1. It is challenging but once you get through the first level it is not as hard as everyne claims it is, I thought it was easier than kZ2, if there is one thing it is is that it is unforgiving(i.e. if you kill an NPC he wont revive)
2. It is not that scary, its atmosphere is dark, one or two levels might be a little
#. the online is amazing in my opinion it does so many innovative things you play with another player but it does not feel like any other co-op