I agree with Shoot2Kyll. I think using the Zapper makes the game so much more fun and adds a realism about it. Nothing feels better than making an awesome sniper shot when you are really using a gun instead of a controller. SO it looks like a goofy space gun or something, but it is a game after all. I've never played it any other way. It does take some time to get used to it, but once you do it is awesome. I use the alpha button configuration. It works on all Wii C.O.D. games.
My next step is to get this bad boy that comes with the new Cabela's came. Looks like an assault rifle and even has a workable scope. The guy at Gamestop said it works really well.