You're right. The problem with these little circles is that, in order to navigate, you need to horizontally move a precise amount of pixels without moving to far away vertically. It's also an issue considering this type of navigation is meant to be used rapidly, going from one circle to another. You usually end up clicking all the circles and not just one.

That's why, when I can, I tend to trigger the navigation on hover and not on click. Google does that as well. It's much less frustrating because it doesn't require to exactly stop on a circle but rather just go through it, and it helps quickly trigger all the circles in a fluid sequenced motion.