This allows a digital preview of the through an "electronic viewfinder" or LCD. In turn, you see precisely what the image look like before you press the shutter

I am pretty locked into the Nikon DSLR system due to price, but for people thinking about the choice between the two systems and new or relatively new to digital photography the above may be a very good reason, WYSISYG - the What You See Is What You Get, view finder thing. I can't tell you how many times I have taken a lot of pictures only to remember and forget that I had my settings way way off, (I use the manual choice most of the time since I am trying to learn the ins and outs of good photography) I do not have my eye trained yet to full look at the info in the view finder, and I sometimes miss that I had a very high or very low ISO selected.