The "problem" with the card is that it doesn't jive with what people expect unless they have a very clear understanding of how the move action works. I think they could have avoided all of these problems and made it more intuitive with some better wording, something like:
"Use after you resolve a (special action) during your activation to perform 1 additional action. At the end of your activation you become stunned."
Edit: To be clear, I understand that this changes how the card works, but to my mind this probably still matches the idea behind the card and ends up with things seeming less confusing/rules-lawyery.
Edited by ManateeX