I love GMail -- except for the spam filtering. It's broken in an impressive way. Google's spam filters miss a lot of spam (so it shows up in my inbox) and they label a lot of my email as spam when it isn't (possibly a problem with how they handle redirects). Of course since GMail is a free/beta product there's
My regular ISP, using standard open source spam management solutions, does a far better job.
Update: When you mark a message as 'not spam', GMail is supposed to add the sender to one's contact list. Contacts are supposed to be 'white listed'. This is broken, GMail is not always adding the sender correctly. I'm adding the sender for miscategorized email manually to my contacts list.