Finished it a few days ago.
I'm a little disappointed, especially as it's following in the wake of SS1 and SS2. There was very little choice, moral or otherwise. Kind of the same way Fable advertised choice as a massive breakthrough feature and failed to come through on - meaning giving the player hugely polarised choices which have little to no effect on the game.
I can't help but feel it's full potential has been dumbed down for the console market from an intriguing and subtle FPS/RPG to being merely an FPS-with-bells-on.
That said, it's definitely the best game of the year so far and is still thoroughly enjoyable. Art direction and content is second to none (well, maybe on a par with SotC), the AI is pretty damned nifty, storyline... is above average, script's sweet, beautifully crafted levels... an all-round good game.
As usual, this dude's review is spot on (no worries, there are no spoilers).