I've played Dark Souls first, and am now currently playing Demon's Souls.
I personally like Dark Souls more because I feel it has the better atmosphere. Demon Souls does, in fact, seem more challenging.
One thing I have to point out is that there is alot more freedom to customize your weapons in Dark Souls. In Demon's Souls I feel like I'm forced to use the best weapon I find with little room for upgrade paths.
Regardless of these two differences, both games are absolutely amazing and deserve to be played. Dark Souls is my favorite game this gen and Demon's Souls isn't too far behind.
I don't know why people tell me to get a life. I'm a gamer, I have lots of lives!







