I just installed it in my site.
I get an average of 7 spam registrations in a day in my website. let me see how good this works avoiding spams from registrations... by forum settings spams have been avoided from posting but at the cost of avoiding guests from posting. let us see how this works good.
let me take a week or so and get back with my feedback. wish me luck
update: 04/17
Its now 24hrs since I installed this bot and it works fine. not a single bot registration till now. I think phpBB could go ahead and make this part of their phpBB package. Bots exploit the visual confirmation by the background of the image, its a single color background which is identified and removed .. leaving behind the visual code which can be read. This Mod uses images as background so multiple color so bots is not able to exploit. good job.