I stopped last night at the beginning of Chapter 14 I believe.
While this game has certainly had some crazy high points already, I feel like Naughty Dog keeps slowing things down too frequently. Extended periods of slowing down. The first two games had slower moments, which are great, and let you catch your breath. But this game has segments where you literally don't shoot a gun for nearly an hour. It also has far more puzzles than the previous two games, at least to this point in the game. Don't know if the rest of the game has any.
It just feels like they tweaked things a little too far in another direction. Pacing changes are too drawn out, puzzles are too vague with the clues, making them take longer to figure out, slowing down the pace more. Then you've got story elements that go on for a bit too long. They take the gun out of your hand often, and sometimes for long periods of time. Then they jacked up the enemies rushing you, to extreme levels at times. I'm shooting dudes, only to be forced into another fist fight, with mechanics that just aren't as engaging as I'd like them to be.
Yes, the shooting action has finally gotten crazy around Chapter 13/14, and it's awesome, but I just have this sneaking feeling they're going to take away my fun toys again soon. :/
Even with that said, this is a very good game. I'm just not so sure it's got the overall fun factor, and perfect pacing that Uncharted 2 had.