There's no issue with installing standard Dropbox on a regular Windows 8 machine. If you'd like to be able to browse your Dropbox folders in a modern-style Windows 8 environment, you can now install a Windows 8-specific app for viewing and accessing files — but weirdly, it doesn't actually let you upload new files from your local hard drive.
The Windows 8 app lets you browse photos, watch videos, and share that content with others using Windows 8 charms. However, you can't upload files into Dropbox, and you can't access data from your Dropbox folders in other Windows 8 apps.
For users running Windows RT (which won't run anything other than Windows 8 apps), this is a potential solution: for everyone else, sticking with the Windows 7 version of Dropbox makes more sense.
Hello, Windows 8. Dropbox is here! [Dropbox Blog]