It runs great for me, all settings maxed, at 1920x1080.
2500K @ 4.2GHz, 8GB 1600DDR, XFX HD6850 with a slight OC.
No slowdowns, stuttering, etc.
The only problem I've had is sometimes when it starts I have to change the resolution to something else and back to 1080 because is displays weird shadows and overlapping while in game (it's hard to describe).
The only gameplay weirdness is when you try to talk to a quest character and have your gun out, the cutscene starts, they say put your gun away, then the cutscene restarts from the beginning. More funny than anything.
On this playthrough I did the police station the stealth way and right when I was about to leave after doing the objectives, I decided to go back and take out the entire force. It is Detroit after all. When I walked out the front door, I was greeted by gunfire, and when I died and reloaded, it started me outside with three cops shooting at me. I had to turn as fast as I could to go back inside to heal as I was left with single digit energy. I could have used an earlier checkpoint, if that hadn't worked, so no big deal there either.
Other than that, it's the most enjoyable single player game I've played since Borderlands or Just Cause 2 for just messing around.