A stellar experience that is Irréversible changed by...a thing. Even talking about what I don't like about the game is a spoiler. All I can really say is there is a narrative shift that occurs each 1/3 part of the game.

You are not buying what is being sold to you, and if that is a concern, then you should absolutely pirate it before paying full price. You either love or hate this shit, and let me tell you, I fucking loathe it.