Uncharted lacks a hook.
I love colorful games, I love shooting and I love Uncharted's graphics but I have no desire to play it and it certainly isn't making me consider buying a PS3 because I don't find the story appealing and I'd wager that most mainstream people don't at first glace. Uncharted is heavily inspired by Indiana Jones, it's a story about a guy who fights pirates in the jungle. I'm sorry but in this day and age that's not enough to sell people on a game or on a movie. Yes, **** Raider did very well but **** Raider had 2 things Uncharted doesn't: boobs (don't kid yourself, Lara Croft was a big selling point for 13 year olds at the time), and gameplay that really hadn't been seen before.
Uncharted is beautiful and looks extremely polished but extremely generic. My casual gamer friends have talked about Killzone, Assassin's Creed and even Heavenly Sword but none of them even seemed to be aware of Uncharted and this is why the game will sell poorly worldwide.