I played the demo the other day and it was decent. Nothing to write home about IMO. The looked,controlled and felt like Shank, but with the emphasis being on stealth instead of straight up action. My biggest complaint in the demo is one that plagues almost all stealth games, at least older ones. If you get caught you're fucked. Even with a sword it seemed to take 50 slices to take a single enemy down, who of course has a machine gun. So you may as well start over at the previous checkpoint. I would hope you get better or upgraded weapons down the line at lest to alleviate that issue.
You never get upgraded combat to handle it out in the open. Just like Batman, if you are spotted by guys with guns, you're dead if you try to stay and fight. You do, however, get a ton of different means to escape and regroup. However, that being said, the thing about this game that breaks the stealth game problems is that the checkpoints are set up perfectly. It never punishes you for dying, nor does it punish you for just restarting at the previous checkpoint (it doesn't even punish you in the sense that if you get spotted while trying to achieve a goal that requires not getting spotted, you can just reload, no harm done). I would hate for it to allow you to upgrade into some action badass that doesn't need to worry about being caught, because it's a stealth game.
I got the impression there was nothing about this game that was going to get you interested at this point given your somewhat contrary nature ($15 rawr!), but at least you tried the demo finally.