You see, if you're drawing in Illustrator and you start drawing a new line too close to where you stopped the previous one, the software deletes the old line and replaces it with the new one. I don't know why somebody thought this was a useful feature. Perhaps Adobe's programmers thought that everyone likes to draw in one, long, unbroken stroke?
The only way to stop Illustrator from deleting the line you just drew is to deselect it. In older versions of Illustrator, this was Cmd + D. Annoying, but not too much trouble. However, in CS3, they've changed the keyboard shortcut for deselect to Shift + Cmd + A, a whole new "three-finger salute." At least I can change it back in the preferences, but it's still annoying.
In FreeHand, I could just draw, with a tool that responded to the pressure of my pen. Look at the difference. Here's some doodles I drew in FreeHand:
And here's one I drew in Illustrator, with a pencil and a brush line:
See how one-dimensional the brush looks? I miss FreeHand.