Sadly despite being gold certified for Eyefinity, DmC is unplayable at multimonitor resolutions - see http://www.wsgf.org/forums/viewtopic.php?f=64&t=25342 and http://www.youtube.com/watch?v=UQ0QiYLOZSE (whilst the video is taken on an nVidia Surround setup the zooming issue affects Eyefinity as well, apparently).  Can AMD perhaps help the developer sort this out?

Edit: might help to actually say what the issue is as well as linking to discussion of it - the game starts out ok, proper horizontal+ behaviour in multimonitor, but then keeps zooming out and out during gameplay until it zooms so far that the player character is too small in the middle of the screen for you to see what's going on.

Edit edit:  New patch fixes it apparently, woo!