Firstly, thanks you guys develop this amazing extension. I have a suggestion for this extension.
For now ezsurvey put the error messages at the begin of the form. When i used ezsurvey in our project, the customer always demand putting the error message near the question (Above or below). So i have to put error message for each question if the answer for that question is wrong. Consider following code snippet:
<label>What your email?
<span>Please answer this question as well</span> <!-- This is error message -->
<input type="text" name="some name" value="" />
So, we got error message nearby the question. And the user can quickly know what kind of problem with his input and where is problem. I think it is better for user's experience.