I'm not much of an adventure-game fan, I prefer RPG-s, but Fahrenheit became my favourite.
My brother showed me a few videos of Heavy Rain. I was amazed and utterly impressed. I wanted to play it so badly, but obviously I couldn't so I started to look for similar games, that's how I got to know about Fahrenheit. A game about lives, not characters, a game about an epic story of decisions.
I don't want to spoil any fun, so I won't write too much about the plot, it's far enough to read the review, but actually that's not the best part of the game: the decisions make Fahrenheit one of the best games out there. I can only give Mass Effect as an example, where your decisions made a great impact on the story line. No game could done this before it ... apparently Fahrenheit was the only one which could get near it's level, in fact far succeeded it. Every choice, every decision you make through the game changes something in the game. I can only recommend it!