So, I had never played this before. But when I saw the sale (midweek madness, so still up), and the fact that all my friends say it's awesome and why-the-fuck-haven't-you-played-it, I thought why not. And now I just finished it. 12 hours down, NG+ started, and all objectives completed in normal playthrough. I love stealth games, and this had me seriously hooked. I think I played for five hours straight first sitting.
So, any other newcomers to Mark of the Ninja? The game is gorgeous on PC. Especially during the old castle part in the lightning storm (location spoiler).