I played for 3 hours last night, and my quick thoughts no spoilers:
Intro: I didn't get why it was being hyped as the best intro ever, honestly. From a design standpoint I loved it, and how ND marries narrative and gameplay. From a narrative standpoint, it was predictable. Then again, a lot of you guys couldn't resist dropping what I'm sure you all considered vague hints, but, to me, were loud abd clear. I still thought the intri was great and set the tone of the game excellently, but yeah, dat hyperbole.
Graphics: I also don't know what kind of TVs you guys are playing the game on, but I'm playing on a 40' 720p Samsung and the game looks amazing. The visuals look sharp, texture work is excellent, and so far the framerate us rock solid. I'm loving the attention to detail and the atmosphere. I've just been soaking it up. The audio is fantastic as well.
Story: Hey, there's actually a narrative and characterization here! I'm loving the characters and interactions so far, and the story is compelling. I'm interested in seeing where it goes. Voice acting is more than just top notch. As is the writing. Naughty Dog has a gift for getting some great talent in their games. Excellent acting here. I also love the worldbuilding tucked away in the collectibles. Great stuff, and helps add layers to the world.
Gameplay: This game reminds me a lot of Demon's/Dark Souls, in that it's very deliberately designed. It's not a third person shooter. It's not Uncharted, and trying to play it like UC will result in a quick death. It's really a stealth game at heart, and being slow and methodical is key. The controls also feel really good and weighty, like Killzone 2. Joel has weight to him.
Yeah, companion AI is funny when they stomp around like morons while I'm bei.g stealthy, but it doesn't break immersion fir me like others. I can't really comment in enemy AI, because I've been stealthing it up and have only been spotted twice, both times being when an enemy turned around as I was about to grab him, so I ended up beating the shit out of him before they could react.
So far, I am loving this game to death, and the praise it's getting is warranted. Sadly, I've been called into the office for OT, so I won't be able to play it again until tonight.