Gmail is mostly impressive -- except for the spam filtering. Creakly old Yahoo mail, or even my local ISP, does a much better job at separating the wheat from the chaff.
Gmail errs in both directions. It puts spam in my inbox, and not-spam in my spambox. It invariably filters comment submissions from blogger into the spambox -- even though both Blogger and Gmail are Google properties. Google's a multi-headed monster, and the heads aren't necessarily on good terms.