While photographers have embraced "more pixels is better", there are some advocates of "pixel quality" instead of quantity.  This sounds good but I have never seen any real statistics that support either theory.  Besides, it also a little confusing wading through all the noise so I decided to put pixels into perspective. 

I recently purchased a very expensive 12 megapixel D700 whose major drawback is that Nikon should have made it a 24 megapixel camera.  I'm beginning to think I'm also a pixel counter.  So what is the "big" difference between 12 and 24 mega pixels? 

The answer is: one entire print size.  Basically, at 12 mega pixels, I can generate 11"x14" prints that meet my requirements.  At 24 mega pixels, I can generate a 16"x20" print that is the equal (per square inch) of the 11x14.

In short, the number of pixels does make a difference.  I am aware that there are some professionals that can do incredible things with fewer pixels but I'm not one of them.

The math is demonstrated below.