I used it to teach myself about photography in depth; my first real understanding of "exposure" came on the 5D2. The statistics show that over the years I used this, I attached over 33 lenses, so the only thing ever holding me back were my own limitations.
The reason for the eventual sell of this camera was because of its large size. By the end, I was shooting most often with the smallest lens in Canon's lineup, and even still the camera remained huge and bulky. I was spoiled by the smaller sizes of rangefinder cameras, so when digital "mirrorless" cameras came into their own, they instantly had my attention. It was a tough decision to sell the 5D2, but it was still worth a chunk of change on the secondhand market, and I dislike clutter, so I did it. No regrets, but it was not a bad camera by any means. Anyone who tells you otherwise is pushing an agenda.
All that said, I took many thousands of photos that I am proud of using this camera. Its departure from my life was the end of an era.
I took over 30,000 photos in the five years I owned this camera, so picking favorites is impossible. Instead, here are some of photos I've taken with this camera that I'm proud of: