Still not got it yet but the post is yet to come. I might post impressions later, but not sure. But for those wondering about supernatural elements etc. I don't think you have to worry about that. As far as I'm aware, the story's completely grounded in reality and thus, it can affect you more.
As for what the game plays like, you can find a 'let's play Heavy Rain' on Youtube at: http://www.youtube.com/watch?v=wAh2wKuYxUg&feature=channel
Essentially, as Aliasalpha said, it's like Fahrenheit. Personally, I'd say if you liked the first two thirds of Fahrenheit/Indigo Prophecy, you'll enjoy this game. But take that with a grain of salt as I haven't actually played the game yet.