I used exposure compensation for a corporate photography group shot and made the mistake of leaving it on for my next shoot in manual where I did not need to compensate!

I use exposure compensation a good amount. I shoot aperture priority most of the time with matrix metering and I find it a quick and easy way to get a good correct exposure that way. For example you are shooting a snow scene you can just pick your aperture, use matrix metering and dial in some + exposure compensation to get the snow looking white. Or another example is silhouettes pick your aperture, compose, focus, and dial in some - exposure compensation like this pic http://www.flickr.com/photos/josephsestiliphotography/6914263969/in/set-72157629437219167 Can I do the same thing using manually exposure mode yes but for me I find it quicker and easier to shoot with aperture priority and exposure comp in matrix metering mode. I usually shoot none posed more capture the moment type of shots that I need to be fast or the moment or animal is gone.