The enterprise plan is worth it for the number of sites we have this plugin installed on. It's pretty easy to use and the installation and activation is as straight-forward as a WordPress plugin can be. Once the plugin has been activated, you'll see a drastic reduction in spam comments. Several other popular WordPress plugins integrate with Akismet to benefit from the spam prevention capabilities it provides as well, and the API has always been reliable. The reports Akismet provides with the paid plans are also interesting to see (and provide a quick reference to demonstrate the ROI in time saved) Review collected by and hosted on G2.com.
It doesn't seem fair to criticize Akismet for this but as with any spam prevention solution, it's not perfect. Sometimes spam slips through the cracks, and other times legitimate comments are going to be erroneously marked as spam. Akismet does a great job, but it is most effective when it is a part of a larger collection of spam prevention tools, eg captchas and honeypots. Review collected by and hosted on G2.com.
