It's great and horribly addictive. You can track hourly traffic, referring websites, keywords that led people to your site and lots of other cool stuff, including where they are in the world.
The map above shows the location of TIGS readers from the last week or so - I think it's interesting as a reflection of the global advertising village - it certainly seems to cluster around key advertising centres, with the exception of Japan - where are you Dentsu?
Google Analytics comes out of beta today, it was previously only available by invitation, so if you are a blogger I suggest you head over there and register - like pretty much everything from Google its free and works brilliantly.
PS. Did the titles of this post trigger a jingle refrain in any Brits? Sorry. But jingles have power. Low involvement processing and all that.