Good question.
My personal oppinion is that Microsoft looks nicer and has more options, while Google has better usuability. Microsoft is often a little slow, but has some great perks like the tree view (once you've got your grip on it, it can be very usefull). Also the demographics in MS are better, as Google has none (appart form location).
Other MS plus points are it's counting of visitor numbers. Microsoft counts a unique visitor as it enters the site. Google counts them for each page seperately and them adds them up, showing a larger number in general.
Another difference is in the natural referal details. MS differentiates between the location and type of searches, even if they have al been in Google. Also the effect of social networks like StumbleUpon are different. Google accounts them as referals, while MS accounts that traffic to 'direct traffic'.
Selecting date ranges for your reports is available in both systems. Google was fastest with this, but with the new Silverlight plugin, MS has an edge.
Getting to your information is a lot harder in Microsoft Analytics though, as you generally need a lot of clicks to get to where you need to be.
Google still remains the standard and some think the better of the two. However, please remember that Microsoft is still in Beta phase and is still improving thier tool as we speak.
I still believe Microsoft will eventually win or, at least, get a draw.
Two intersting posts on the subject;
http://www.businesshut.com/blog/2008/03 ... ytics.htmlhttp://www.whencanistop.com/2008/05/goo ... enter.htmlHope this helped! And are there any other oppinions??