I think it's a really cool idea, and more games could use it. It lets you experience the story from different perspectives. And if you don't click with the main character, there's always a chance you'll like one of the other characters better :).
Norn9 really surprised me at first, because the prologue featured a different character, and I was worried it was a different game than the one I wanted. Then came the choice of protagonist, which surprised me even more, because I hadn't read about that feature in the game description at all.