This seems like an extremely useful class, however I have run into a few problems along the way which I am hoping you can help me out with these.
The main problem I am having with this class is taht there appears to be a lot more information tied into the class and I am unsure on its functionality.
As far as I can tell the example index.php requires a user to be logged in to save a comment and there is no way for a user to be logged in on index.php. When I try to insert a comment an invalid value is given for the SQL insert statement and the comment is not inserted into the table.
Also just so you know the fonts folder is missing for the captcha to display the font needed. When this is class is run the captcha appears blank as it cannot find a font. Maybe a fonts file with some trial fonts could be included with the package as the user cannot read the font and they will not be able to insert a comment.
I know English is not your first language, so please respond if these points are not clear.