FUCK YES.
Haven't played Dark Souls 2 yet, but aweriuaweufajwefoiawehfla I fucking love Demon's Souls, I never shut up about it when it first came out.
Seriously, absolutely perfect atmosphere, minimal but effective story, memorable areas, creative creature design both aesthetically and technically, fucking epic boss fights, and an incredibly well done control system. Oh, and did I mention PVP IN THE FUCKING SHRINE OF STORMS?
10/10 would touch the demon inside
Dark Souls is pretty good too, in comparison to most other title, but honestly it let me down tremendously after the brilliance of Demon's Souls. The areas felt rushed, some situations seemed to have artificial difficulty, atmosphere was still good but not flawless like it's predecessor, and the graphics and animation seemed to be of slightly lower quality. But I was able to enjoy it more after taking a few months break, and playing it as Dark Souls and not Demon's Souls 2.