You guys need to calm down, while it's true that I was also nervous about AMD in start but this is no longer the case thanks to some mods here for explanation. First TW3 is only using couple of GameWorks features not a whole bunch. Here they are
1) HBAO+
2) HairWorks
3) PhysX
4) APEX Clothing & Destruction
5) TXAA & MFAA (Most probably).
1) Now I have tested several games using HBAO+ on my R9 290 and it doesn't do any bigger hit on AMD than it does on Nvidia, it's an old thinking that HBAO+ hit AMD cards really hard. AMD now have improved their drivers to work well with this, of course it has some additional performance hit compared to other AO techs but it's about same on both AMD & Nvidia.
2) HairWorks is a demanding feature yes, the latest game that used it is FarCry 4 and according to a discussion on another thread it hits my R9 290 and a GTX 970 almost same. A 970 also start to struggle when there are 4 fur animals on screen, same goes for R9 290. Initial iterations of HairWorks tend to hit AMD really hard (example Call of Duty: Ghosts) but now it's much better and with TW3 it might get even better.
3) For AMD users PhysX will get offloaded to CPU so you need a powerful CPU for that. A Haswell i5 4690k or i7 4790k is the best pick at the moment. Also according to Guy and other mods here, the new PhysX SDK 3.x works really well on CPUs so you have nothing much to worry about. I have tested this in Metro Redux myself. Advanced PhysX (which was a pain before) is perfectly playable now on my i5 4690k with R9 290 achieving 60 fps easily at max settings.
4) APEX Clothing & Destruction is a CPU feature, already working well in games like Batman.
5) TXAA & MFAA are the only things AMD users missing out but we already have MSAA.
So in short AMD users are not missing out any eye candy and HairWorks is a demanding feature for both AMD and Nvidia GPUs.
With that said I have now shifted to GTX 980, not because AMD cards can't handle TW3 or anything but because GTX 980 is the best thing available right now and my PSU cannot handle two R9 290's very well. I know I can wait for new AMD GPUs which look really powerful from speculations but the fact is I have money in my pocket right now and I want to get the best thing available out there, maybe by the time AMD GPUs arrive I no longer have anything to spend.
Keep one thing in mind that regardless of AMD or Nvidia, TW3 is turning out to be a very demanding game so if it doesn't run well on AMD or Nvidia it doesn't mean it's unoptimized or it's happening because of GameWorks, it's just because the game needs more muscle to run well thanks to it's ambitiousness. I have plans to get another 980 near release for SLI and people with AMD should also go for CrossFire setup if they want to max out this game or wait for the new GPUs to arrive. For now single GPU flagships like R9 290X or GTX 980 doesn't seem to achieve 60 fps at ultra settings for this game.