The widget's code integrates easily.
I think the panel with the message should be a little (20%) less in size, at least on my 1600px wide laptop. The panel is nicely designed, but dunno why instead of nice Thanks! message it lefts white rect after submitting my review and doesn't dissapear! This should be fixed asap.
Mainly, this type of interaction should be as sleek as possible. Admins should have more UX options like seconds delay before the panel appears, speed of fade in or type of another animation. This will provide more attentive attitude and more user feedback. I like such quiz widgets on websites.
I think there's a lack of a feature like Would You Like to Take a Short Quiz or Write Us More...