From the few times I've ran it, it focuses more on a case or problem that seems more of this world (e.g. a missing person, a murder, theft). As the investigators dig more into the case, things get more weird (rituals, weird people, hints of magic etc.). The climax is typically a major event that makes no sense to normal logic like a sacrifice taking place to an Eldritch horror or seeing a monster and running. There's a lot of failure that happens to the investigators as it is very hard to roll well in things you're bad at (which is more realistic in my opinion) and it uses a percentile dice system. Library use skill is bad? Can't find the book that just might save your life at the climax. Combat is typically avoided for that reason as taking half your HP as damage knocks you out or worse. Getting stabbed once might lead to you dying very quickly. All this is happening while the investigators are trying to deny the weirdness that is going on to prevent going insane (which today affects gameplay and can yield interesting roleplay).

Overall, it's a different system in which the investigators struggle to survive and realize how insignificant they are to the universe with fun roleplay. Four out of five tentacles, would recommend.

Edit: minor spelling mistakes