I have always appreciated the simplicity and intuitive controls Apple uses and they nailed it with this device.
Most of the people I know that use Apple started with one of their mobile devices as did I. My first Apple product was the iPhone 3G. The pinch to zoom and the swiping just felt like the right motions to use. I then saw my cousin's Macbook that had some of these same features integrated into their trackpad plus a few more.
I'm now using an Apple desktop and I wanted to use the same motions I had seen on the laptop and there entered the Magic trackpad. It works really well between the software I use for Photo editing and video editing. The only thing that I don't feel as comfortable with is the dragging and dropping motion. I can use this function decently, but a generic mouse does the trick faster for me so I use them both.
Apple has already developed a second version of this trackpad and I'm curious to see if it solves this efficiency issue of the drag and drop, but I am satisfied with the current one as is.