I upgraded my Win7 PC to Win8 a couple of days ago and have been noticing that Metro Apps don’t completely communicate with traditional Windows applications. The extent of this ‘feature’ just became obvious when I opened my ‘old Windows Kindle application’ on the traditional desktop and had all of my downloaded books. BUT when I opened the ‘new Metro Kindle app’, while I was automatically logged into my Kindle account, I did not have any downloaded books. I went and checked my Amazon Kindle account page and sure enough I now have TWO separate Kindle accounts assigned to the same PC. I suggest you point this feature out to people.
That's going to present some interesting problems for anyone who upgrades, isn't it? I was half expecting for the new app to replace the old one, not install alongside. Since it didn't anyone who is currently using the Windows 7 app will need to keep the existing app after they upgrade, Otherwise they'll need to download all their ebooks again.
But that is not entirely the fault of Microsoft. Amazon is very picky on how they handle DRM, so much so that if you uninstall and reinstall the Kindle app on Windows 7 you will need to redownload all your kindle ebooks. The newly downloaded app won't be able to read any of the ebooks downloaded with the previous app (weird, I know, but true).