I gave this a quick spin since I love survey forms :-)
Overall, the UI is good and easy to use. There are some bugs like:
* I cannot edit the input field title
* Drag and drop breaks too easily
* The submit button looks "disabled". https://form.mightyforms.com/preview/f3874162-4890-452f-8ef1...
* I couldn't figure how to get a public link to the form. Or is only sharing possible?
See https://imgur.com/gnEr6e8 for UI issues
Overall, I think once you have the bugs ironed out, it's ready to launch as a MVP. Good stuff!