Easy to install and to set.
One little thing, I choose reCaptcha, because with cache enabled and myCaptcha the Captchaseems to be cached.
But that's not a real problem because setting reCaptcha is really easy too !
Thanks for this "must have" plugin for CB
If you use joomla cache plugin the image generated in myCaptcha mode will be cached. The plugin store the full html of the page for the next unregistered visitor.
Anyway, It's not a problem at all (from my point of view).