I would NOT use AKISMET as my ONLY defence on my blog!

That would be uber-stupid!

We all need several defence walls against spam. First, check, if the commenter IS human or not. This can be done easily – there are a lot of plugins for that purpose, like ‘Simple Math Comment Spam’ and others, even simpler and more user-friendly ones.

Then, basic protection against pingbacks/trackbacks (check URLs, for instance, using a plugin).

Third comes AKISMET, just in case some SPAM was able to break the first two walls, then comment should be put into moderation/spam moderation.

***

If you don’t use the first two walls, then all spam comments hit you with full-force, and then I have to check everyday tons of spam in my AKISMET moderation queue. This should not be the case! 🙂

So first we need to prevent MOST of the comments from spammers from reaching at all our blogs, then comes AKISMET. Also, why waste bandwidth, IDs from the database (each deleted spam comment wastes one free ID), and time to manually check comments, when this time can be reduced a lot by installing a couple of more anti-spam walls between the spammer and your blog?

Cheers, my $0.02:)