Upload your images to facebook or twitter and they look awesome, but hey… how can they not look awesome if they are like 5′” @ 72dpi.
In real life, and with real clients, the actual 100% view is king, one needs to achieve a good sense of the optics and sensor that is working with, iv’e learned this the hard way.
Having a 7D i assumed at first that any optic would give me the sharpness i was used to, i was wrong. The more resolution a sensor has does not mean that this will have more definition, here is where optics come to play, you might have a nice f2.8 lens but you sure can’t use it indiscriminately on any situation.
More megapixels sometime is something overrated, what i did is i spent many hours on this site http://www.dxomark.com/index.php trying to find out about the sweet spots on different optics.
It helped me a lot in the understanding of the relation between resolution (megapixels) and definition (sharpness).