It's much easier than the previous Splinter Cells, but much more fun at the same time. You can get through it run-n-gun, but it feels far more satisfying to stealth kill, mark and execute like the game wants you to. Tore through it on Normal and Realistic with a death each. In fact, in realistic, I restarted one checkpoint because I alerted the guards and wasn't satisfied with my kill. Sadly, it does not seem there is a 'no kill' route this time, at least not in the level they give you.
Definite buy.