Last night, I worked with the Magnetic Lasso tool and tried to make a selection using it. I liked the choices of adding to a selection, subtracting from a selection, or creating an intersection of two selections. I didn't like how the Magnetic Lasso tool would place points by itself, because it thought it needed one there. I disliked the look of the cursor. It wasn't clear to me where I was going to create a point when I clicked. It wasn't at the cross hair, and it wasn't at a point on the triangle of the icon. Zooming in did not help. After my first pass with the Magnetic Lasso, I had to go back and make corrections many times. It was not a quick process, and the shape I'd chosen to practice on was ideal, with lots of contrast. I gave up and stopped refining my selection long before it was accurate.
The auto selection tools, like the Magnetic Lasso and the Magic Wand, are all fine and dandy but for the most control and the best results the Pen tool is the way to go. The more I try to work with the auto selection tools, the more I believe this. The same task done with the pen tool would have taken less time and given better results.