As other have said, it depends on the game being hunted. Turkey, ducks, etc have different eyesight from deer, elk, moose... I use full camo when Turkey hunting. I do believe it makes a bigger difference there than big game hunting. I don't duck hunt, but I would use full camo there too if I were to start.
In the past I never saw a whole lot of value with camo for big game hunting around here as the state required a large amount of solid blaze orange. Why wear camo on your lower half (which is often shrowded by brush anyway) when you are required to have a solid blob of color on top?
A couple of years ago Utah approved "blaze camo" which would help to break up your outline on a big game hunt. I would happy replace my regular camo vest with a blaze camo vest if anybody around here carried any blaze camo... I plan to start wearing more camo as I see no harm in attempting to break up your outline, even if it's not 100% necessary in all situations.
I also agree that the majority of modern camo for big game hunting is designed to fool the hunter into opening their wallet, and not necessarily properly designed to fool big game. I think modern camo patters are far too busy, with little or no "negative / white space". You end up looking like a big grey blob from a distance. I like the ideas behind ASAT and Predator Camo, but they are a bit harder to find than the more popular brand names.
I recently discovered "Vertigo Camo" that has a basic pattern with lots of negative space on it and comes in "tan" and "white". I personally feel like it breaks up my outline better than the Realtree or Mossy Oak patterns. I plan to try them out this fall.
