I hand-approve all comments (and let pretty much everything through, just in case…because obnoxious spam is NOT going to show up on my watch!).
That said, I have yet to see a single instance of auto-spam in the approval queue. Every single last creeping, festering, crud-mongering piece of spam has gone into the reject queue, automatically. 100% rejection.
That’s darn impressive. Well done, Akismet!