I received the preview version of Uncharted and played through it. It's more than an hour of gameplay and then it stops.
I absolutely love it. The gameplay is very, very smooth. The combat has some great touches, like shooting or throwing grenades from a hanging position, or the ability to walk forward from cover in one movement (instead of getting out of cover and the continuing). The animations are great in almost all cases, such as reloading a gun or performing a roll.
I especially think everybody comes together so well. All the little touches in the combat, combined with the AI of the enemies (they flank you, take cover, and throw grenades) makes for a cool combat experiences. They can also blow up some walls with grenades, taking your cover away, and you can hit them when they throw their grenade so they drop it and explode!
The platforming/exploring part is fun too, although not that difficult. They even reduced the difficulty compared to the Leipzig demo: took away a big jump in the waterfall area.
Cool thing is that you can find treasures and get rewards for special actions (like killing 5 guys in a row with headshots only or killing 3 guys with one explosion). You then unlock movies, skins and other gameplay-things, like faster movement. So this is a game where you want to complete all those tasks and want to find the treasures.
The story is cool so far and the cutscenes have a good mix of cheesy adventure-style, humour and seriousness.
If the game can keep this level of entertainment, it's great. Really great.