Here are two survey apps for iPads that I found good:

Surveypocket: This is just for taking surveys on mobile-devices. It doesn’t have a survey-software of its own, but can be synced to one of two survey tools Survey Analytics/Question Pro. After the survey is completed, you can go to your Question-pro or Survey Analytics account to see the results. Survey Analytics is a sophisticated tool, but at least for our need, we didn't need any advanced features. A simple visual dashboard is what we really needed, but we missed that here. (Dashboard is available, but has limited functionality)

iSurvey: Similar functionality, but I like this one more. Allows creating surveys from the web-version (https://www.isurveysoft.com/). While creating the survey, you can see how the survey would look on your iPad/iPhone in a device mockup against each question. Later, you can assign specific surveys to specific devices that can be used to take the responses. After the survey is complete, you can come back to the web-version to see the results. The dashboard is neat and allows customization with results for selective questions to be included.
    The functionality of iSurvey cannot be compared to traditional survey tools like Surveymonkey, Vovici or Qualtrics (my favorite). So you may miss features like skip-logic or advanced validation. But if you have a simple survey, specifically one that needs to be run in a kiosk mode, this should work.

See question on Quora