How secure is it?

I love the slider captcha. Incredible concept and far superior to all the other captcha plugins I have tried. However I am concerned about one thing. I have had problems in the past with registration spam and bots registering on my system. Have you done any kind of testing to determine how secure this captcha is?

I would appreciate some feedback on this…..

Thanks,

theunvarnished.com

https://www.ads-software.com/plugins/slider-captcha/