I have used this for two sites. Overall, I like the customization options, appearance, and ease of installation. However, the spam is amazing, and none of the options I've tried has made a difference. Some don't appear to work. I've used all the options for captcha, did not allow urls in text (still coming through). When people have commented on this, just referred to the same spam documentation. It's obviously a significant problem with this extension. I also have a problem with the form always showing when it should only show when a link is clicked. Others have also reported this, but the developer seems to be unable to fix this. Wish these items could be fixed -- love it otherwise, but these two issues are a problem.
Hi, regarding spam, see above (in description of the extension).
Unfortunately, I cannot fix human behaviour. Spammers like all kind of form input fields and all kind of form input fields are spammed. :-(
But really no idea what is wrong on your server. For example, Akismet removes over 95% of spam (including human spammers) in my guestbook. :idea: