nVidia's Gameworks games run so poorly on AMD hardware that it is not hard to understand why Gameworks is be bad for gamers. This isn't advanced critical thinking. Gameworks lays a very bad path for a future of gaming cards in which we want competition on raw performance and instead pits them on what crap like gameworks developers will be lured to use.
Bringing mantle in is conflation, it's completely different than gameworks. Though similarities, Mantle is not widely adpoted either, and is similarly a divicisive effort in gaming. The cards need to compete on open standards. Mantle is open, gameworks is closed. Nvidia controls gameworks and it causes eyebrow rising poor performance on it's competitons cards. Nvidia has enough good stuff going, that they don't need to garner support through crap like underhanded use of gameworks in games.
Sorry for rant. Not directed at anyone, just at nVidia and gameworks and my impression of how bad this is for future of great and games and legit comptetition between our brands.