I like Akismet, and it’s undeniably effective in stopping the vast majority of spam, but it adds a huge number of comments to the database and a very small percentage of comments still get through to my moderation queue.
It’s annoying to find comments in my moderation queue, but what I really object to is the thousands of records that are added to the database each month that I don’t see.
In the screenshot below, January through April show very few spam comments being detected by Akismet. This is because I was using my cache-friendly method for reducing WordPress comment spam to block spam comments even before Akismet analyzed them.
In May, I moved hosting providers to asmallorange.com and started with a fresh install of WordPress without implementing my custom spam method, which admittedly was not ideal because it involved changing core files. This left only Akismet between the spammers and my WordPress database. Since that time, instead of 150 or fewer spam comments per month making it into my WordPress database, Akismet was on pace to let in over 10,000.