In the current pre-release builds we’ve seen, the Ribbon is a serious work in progress and is quite unattractive. It’s unclear whether Microsoft intends to move forward with this UI as-is, or whether it will appear only in certain UI types. Based on what we’re seeing, however, it does seem that there will at least be a toggle to disable this top-heavy UI. So if you don’t like the Ribbon in Windows Explorer, hopefully you’ll be able to turn it off.