You can take this review with a grain of salt, since there are many users that are happy with the Bad Behavior plugin, but I personally won't use it again. If what had happened to me happened when I had more content on my blog, I would have been HIGHLY upset! As it turned out, it was a minor hassle to re-set everything, but no lasting harm done.
Specifically, today when I tried to log in to the admin panel, I was blocked by Bad Behavior. For some reason, it marked my IP address as an offending spammer. When I tried to resolve it, I couldn't get into my MySQL server to fix it. Using my FTP program to remove the files didn't help, either, and consulting the Bad Behavior creator's website yielded a forum with a LOT of complaints citing the same problem. The solution noted on the website was of no help.
Therefore, I essentially lost my entire WordPress blog. To solve the situation, I reinstalled the entire site and reloaded all of my settings.
If I had to do this when I had more content on my site, I would have been devastated! Therefore, even though there are no guarantees on ANY plugin for WordPress blogs, in my opinion you would use "Bad Behavior" at the risk of being forever locked out of your own blog.