I guess they have awesome scale and lighting. Also, the main character models are high quality and the animation is top notch. Animation quality goes a long way and, in the case of Uncharted, combined with how colorful it is the game does very well of hiding it's flaws. Dark games , or ones who have color palettes closer to the greys and browns are harder to jump at you the same way. If you look close enough you can see where they both struggle like in any other game.
I think much of the hyperbole comes from the exclusive factor sadly. They are very pretty games, top of the line, but that doesn't mean anything else isn't.