Simple question that blocks most spambots (and paid robots) by making them answer a common sense question
It's straightforward and for me, it stopped the bots dead in their tracks. I like the suggestion of multiple, randomized questions, that would make it mission impossible for bots to be programmed.
Quick to install, performing just as I expected when I ran some tests.
This plugin together with Stop Spammers Plugin and possibly some other alternatives is simply the best defense against automated comment spam.
I have only one suggestion for future versions - implement a feature where the administrator can make randomized Q&A, this could make the plugin even better - because automated spam bots can actually learn. So using randomized Q&A could perhaps make it better.
Good work, in any case.