Between midnight Friday and 11:00am Monday, I received over 160 spams. SpamAssassin stopped all but five of them. SpamAssassin misidentified 2 legitimate messages as spam; both were unimportant mailing list messages from a user whose site is frequently used to send spam. (If I needed to correspond with this user on a regular basis, I'd add his name to my whitelist--or help educate him.)
If you don't need a public e-mail address, let me suggest a new rule: Never give your real e-mail address to anybody you don't know. This includes online vendors. If necessary, use a throwaway webmail address instead.
Content-based spam filtering is extremely good, and is improving rapidly. Just don't send me any e-mail about hot stock picks involving real estate companies in Nigeria that specialize in toner cartridge factories, and there shouldn't be any problem.