This discussion piqued my curiosity so I bit the bullet and got the game. I tinkered around with the settings and the game runs great on 5850 Crossfire @ 2560x1600
as long as you disable Advanced DOF and Tesselation. I get 45-70FPS so far (only played about 5 minutes), running completely smoothly on the 10.3a Cats. If I turn on Advanced DOF
or Tesselation, FPS crashes to about 20-30FPS. If I turn on both, it's unplayable at 1-3FPS. What's even more interesting is if I turn all settings (via the "Quality" option) down to low, but leave the game in DX11 and with Advanced DOF and Tesselation on, the performance doesn't improve. This isn't a frame buffer issue - it's the drivers, the implementation, etc. - something isn't playing nice here with these two features.
What's also interesting is the minimal impact that Tesselation and and Advanced DOF have on image quality. Here's two screenshots from the first minute of the game. I tried to line up the NPC's head to make it easier, but the motion blur kind of screwed up his helmet in one shot. Either way, Tesselation and Advanced DOF are on on the left screen shot, and they're off on the right. Like I said, it's 1-3FPS vs. 55FPS (in this shot) for performance. I also zoomed in on the NPC model and did a side by side in GIMP so you can see the effects of Tesselation on a character model better.

I'm not impressed, considering the performance penalty. Looking at the side-by-side comparison, the arm pack is a little more puffy and the shoulder armor plate is rounder with tesselation on. However, the textures also appear more muddied/blurry. I can't really see any effect of Advanced DOF, but maybe that's more prominent outside. In either case, totally not worth it. I'll turn the two options on here and there when I'm playing to keep checking, but these just look more like unoptimized throw-ins rather than game changing enhancements.