Eh, I think a lot of people have played the demo but most didn't go much further than that because it wasn't that great of a game. It's not it's a bad game, it's just nothing special and that's why it usually isn't talked about.
It's not good enough for people to hype beyond belief and it's not bad enough for people to constantly mock. It's just there. I would say try the demo first.
I'd disagree. The game was brilliant.
One of the few games that uses the Sixaxis well and it also has a very deep, involving story.