Intensity is new. It has 40 new guns. It has 12 classes. Yes, classes. Intensity has a class system, and it's a very extensive one with tons of class kits. Those classes affect your combat attributes, loadout, and more. The AI has been totally revamped.
Pretty cool news for the COD community, huh? And you can download it right now. Go get it here: http://callofduty.filefront.com/file/Intensity_SP_Total_Conversion;32062