Mass Effect 3 is a sci-fi action RPG, its played from a 3rd person perspective and is heavy story driven. The multi-monitor support in this game is fairly good rendering is horizontal plus in most cases, the only issues are the HUD and menus. The HUD is placed on the far edges of the screen so its not much use, and the menus are vertical minus making some of them unusable. Luckily again helifax has made a fix for it which can be found in the link below.
Mass Effect 3, Original resolution was 5040x1050 aspect ratio of (48:10). If you are running a resolution with a width higher then 1920 (30'' monitor or multi monitor) set quality to original and view in fullscreen.
This video shows a story mission in the game but doesn't contain any real spoliers.