Now that I have a brand spanking new Xbox 360 slim, the first game I wanted to give a go on it was the VERY mature RPG Witcher 2. This game is brutal if you don't think. It doesn't hold your hand. It doesn't put you in linear rails and prevent you from exploring, experimenting, and crafting just about anything you'd want to do in your playthrough. So far this is an engaging, if often text heavy game, and so far I'm loving it with as much hating it for both its boldness as well as its tough enemy encounters.
I'd have to say that, if you expect this game to be easy, if you expect this game to roll over and play dead, if you expect to be this uber-god right out of the gate that can wade into a wall of enemies and miraculously survive the encounter, then you are in for a world of hurt. Not to mention deja-vu as you watch one Game Over Screen after another go flying by.
Though not as brutal as Demons Souls, or its spiritual successor Dark Souls, it is a game that will reward the thinker just as fast as punish the foolish all the same.
Beyond the occasional texture pop-in (ala Mass Efffect 1) The Witcher 2 is an exceptional game all around.
By the by; musically, expect "The Howling Wolf" to be on your personal favorites list (just below Skyrim's Dovahkiin battle song). It's that good.