The "high Performance" specs say a GTX 680. With a card like that you could probably completely max this game and it would still be "playable" although probably not at 60 fps. I'd say a 660 ti can easily run this game on very high, judging from far cry 3 and a gtx 670 can pretty much max that game without super high AA. A 670 can almost certainly run it on ultra without AA at 1080p, so no worries, it will look and play phenomenal on a 660ti.
You definitely won't be able to completely MAX the game, but really that doesn't matter much at the end of the day.
I wonder how it will fair on my GTX 560. I even get around 35 fps on ultra without AA in Far Cry 3, so even I can probably achieve 40 fps on decent settings.