Have you seen that Microsoft launched Virtual Earth? Yeah, it's a rip off of Google Maps and Google Earth I guess, but it kind of sucks.
For example, their image data is a bit old, or of poor quality. Not only can you see the World Trade Center, but the image was taken apparently at dusk given that the shadows of NYC buildings block out virtually everything. You may have also heard about how Apple headquarters doesn't exist either.
I don't much care for it just because the UI sucks. I mean, why would permalink open up a little window? You can't drag the zoom slider. The only thing I really like is that it will fill the entire browser window with images.
I guess it just reeks of "me too." I'm generally a Microsoft fan boy, but I guess I just don't entirely get the point. (After installing Google Earth, I felt similarly, I might add.)