DRM Controversy
There is a problem with the DRM on this game.  Ubisoft promised to release it with no DRM, but apparently released it with the DRM in place.  They have since patched to remove the DRM, imperfectly.  Here are some topics on Valve's Steam forums discussing the matter.  (You can purchase the game via Steam.)

http://forums.steampowered.com/forums/showthread.php?t=2327958

http://forums.steampowered.com/forums/showthread.php?t=2266373

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