First of all: Please STOP writing reviews without even read the description and tried the plugin for at least 1 minute. People looking for solutions can't lose time to understand why some assessments are low only to find that they were written for no reason. Thank you
Talking about WebEngage (free version) in my opinion is really useful and works very well. I tried a survey and everything went smooth.
The admnistration area is pretty simple and the plugin also provide Google Analytics integration.
All pro options like: Leave intent targeting (exit survey) or Minimum number of page(s) viewed by a visitor in a session deserve to be paid.
So the plugin is great and even if I really understand the monthly Subscription due to SSL, number of administrators and all other technical stuff, $29 for a small site like mine is too much for the lack of: Themes & layout options, Customizable messages,Survey Welcome Note and maybe the possibility to customize the notification email.