No consolitis. There's a whole lot of interface options that you can toggle, full key binding options and sensitivity settings for the mouse as well as an FOV slider in the graphics options. Mouse and keyboard combo feels better than a gamepad (tried it with a Logitech F310). The PC version also has UI additions, like the ability to bind weapons and powers to the 1-9 keys instead of using the console version's radial menu, which is nice. And hey, you can lean left and right. No "this game isn't balanced for leaning" bullshit.
The graphics options themselves are a little bare bones (Texture detail, Model detail, Light Shafts, FXAA and !Rat Shadows!), but the game ain't no graphical powerhouse so it's not a problem really. I do feel they should have included higher resolution textures for the PC though. Lackluster graphics aside, I think Arkane did a great job with the PC version. The good news is that older hardware will have no problem running this game. My rig is getting on in years (Q6600 CPU, 6GB RAM, ATI 4800) and yet I have no problem maxing the game out with AA and AF included.
Edit : I've spent around two hours on the first assassination mission alone, exploring and retrying various methods of murder.
There's a lot of variety in regards to how you go about the assassinations. Reminds me of Hitman, but with far more freedom. On one attempt with the first guy, I used blink to teleport to the rafters of his meeting hall. He entered the room with his captain of the guard, engaged in conversation. I was wielding a mini crossbow in my left hand and a blade in the right -- I fired a sleeping bolt at the captain as I simultaneously leapt from the rafters towards the target. The bolt incapacitated the captain just as I landed on top of the Overseer, running him through with my blade. Both fell without a word of alarm.
On another try, I bulled into and loudly killed them both. Guards came rushing in, so I ducked around a corner and possessed a nearby rat. I scurried right under their feet and beat a hasty retreat in my rodent form, whilst they searched in vain. I, unfortunately, ran into one guard who promptly stepped on me. Dead.
On yet another run, I upgraded to the Windblast power instead of Possession. Windblast = FUS DO RAH. I smashed a bottle underneath a window that looks out onto a large courtyard and the Overseer and captain went to investigate. With their backs turned, I snuck up behind and took down the captain with non lethal force, then used Windblast to propel the Overseer out the window where he fell to his death a few floors below.