Mechanically simpler than its sequel, but narratively far superior. The creeping dread and claustrophobic atmosphere to the story as you and your crew find yourselves trapped in Tokyo with demons and other desperate survivors is backed by a great soundtrack featuring heart-pumping beats and wailing guitars.
It also has enough strategical gameplay depth and branching story decisions/endings to facilitate half a dozen or more playthroughs. Of everything I've played, it's no contest the game I've replayed the most, and every year or so I find myself itching to play it again.