It's got a good cast, fun and quick story and charming to quirky endings. Most of the adrenaline really is on the puzzle part, and the plot sort of just keeps you going (the puzzles can get really hard and frustrating at times, though I played before the easier mode patch).
It doesn't really mix into the massive bishoujo adventure games, those are visual novels stuff. They are probably also a lot more varied in that aspect even if only for the higher number of girls to go after. Catherine has just two (plus even a happy alone ending, which I really liked, and maybe those aren't the norm in the dating sims), and it really isn't difficult telling what will get you where. The error and trial in Catherine is 100% on the puzzles.
The hype is probably just niche, maybe marginally someone else, because it's enough of an unusual game.
edit: It's a sexy game but by far there's nothing much explicit in it.
