Played it on hard, as I do all games, because I'm not one to go back and play a game again.
Fantastic game, to date it's my fav PS3 game ever. (I've since bought the Mass Effect Trilogy as a mate said it was the goods after you got past number 1)
I'd also played the uncharted series so I knew what to expect from Naughty Dog and this surpassed my expectations.
I was quite happy with the ending (no spoilers here), and I could see a sequel and would happily play it. It would also make an exceptional stand alone movie. I can't say more than that without giving "some" things away and given how hard I had to work to avoid spoilers so the experience wasn't ruined, I won't risk doing that to anyone else. I should add, I would recommend paying it on hard as it ups the ante in terms of the stealth and survival instinct needed which this game thrives on. I can't remember the exact stats but at the end of the game I had something like 80% accuracy and an absolute heap of head shots, and I'm from a PC gaming background and struggle with shooting on a console, so that just goes to show how careful you will be when every shot counts, I can easily see better players having over 90% accuracy and mjority of kills being head shots or melee/strangle deaths.