I've just played Demon Souls and Dark Souls but yeah, it's definitely not your average hack-n-slash @HBB. Can't say either place in my top 10 of favorite games but they are definitely special. They basically take you on an emotional roller coaster of rage, satisfaction, hatred, joy, despair, accomplishment, existential crisis, and finally nihilism.
EDIT: Thought I was in the gamer's thread?
Controversial opinion: Now that I'm relistening to 1996 albums, I feel more and more like Immolation are kind of hit-and-miss. They have too much fluff in many of their records. Definitely a band that's better heard live than on CD.