I used it in the past, it was ok if you are looking to automate your content and ad video to your site, It can save time and woirk.
If it just automates content writing, no, its not going to help generating revenue unless you have extremely poor grammar and the robot is infact better than you at article quality.
It shouldn't affect the server in any way, but the security of your wordpress installation is a bit of a concern. Many plugins are known to open security loopholes in wordpress and make the setup slower and more prone to attacks. I cant tell for sure if its true for WPRobot, but many plugins have these problems. But after using WPRobot, it may be possible for an experienced hacker to hack your server, because I guess it opens some extra ports