It would be nice to see some examples more than a mockup on the landing page. Both of the builder and the way to fill out the survey.

Is this strictly for surveys or also quizes and other related form-things? Edit: I see now this is for way smaller surveys than I thought. It's basically just a small widget you get from the service.

Shameless plug, I work for Typeform (http://www.typeform.com) where we have a incredibly UI for both building and filling in surveys/forms. Check it out if you're looking for a survery/form/quiz SaaS that have the biggest focus on UX/UI and for more complex forms.