There are two reported flaws with text boxes in surveys, both stemming from the need to have multiple lines.
When you press enter, instead of getting a new line (which you expect), you go to the next question. This means that if the last question in the survey is a text question, you end up inadvertently submitting the survey early. This resulted in a lot of anxiety from users, who then emailed me about the problem.
It is not possible, apparently, to have multiple lines in a textbox.
There are two reported flaws with text boxes in surveys, both stemming from the need to have multiple lines.