Dysport kicked in almost immediately, though Botox typically pops up in two to three days for me. Same level of pain. Less tightness than Botox but seemed to stretch/last a bit longer. So I never felt that cement forehead feeling (which frankly, I love) but it seems to be metabolizing out MUCH more slowly than Botox.
Did it because I was due for Botox and Dysport was offering some challenge rebate thing so it seemed worth a try. I get it in my forehead, my 11's, and will get my crow's feet next time.