In an internal video, which now is also viewable via youtube, Microsoft is showing what is wrong with Google's popular GMail Cloud mail solution:
In short, if you value your privacy, you wouldn't use the service, as GMail is in fact analyzing the content of your mail in order to show advertisements. Which is something the competing Microsoft Office365 offering does not do. While Google's adds are contextual, Microsoft's aren't.
Windows IT Pro's Paul Thurrott presents a nice analysis here. I couldn't agree more, also with his suggestion to turn the video into a public add.