Windows 8 is visually pretty different from any other version of Windows that we've seen before. Microsoft is pushing its new Modern UI in an attempt to reinvent the desktop landscape. Sure, there's also a more traditional 'desktop mode' but even that features some pretty big changes for the average user (no Start button, to name just one). Still, not everything has to change, and there's a good chance your favorite programs will work just fine with the upcoming version of Windows. Check out Tom's Guide's '15 of the Best Windows 7 Programs for Windows 8' for a round up of applications that will still work seamlessly with Windows 8.
In many ways, Windows 8 is just a reskinning of its older counterpart, dropping the Start Menu orientation in favor of the tile-based "Start screen" similar to that of Windows Phone 7.
It takes a little getting used to, but, once you get past Windows 8's new interface quirks, you'll enjoy the relative zippiness compared to Windows 7, which itself is no slouch (provided it's run on a properly-equipped PC).
Yes, there are some programs that do crash on Windows 8. Again, it's just a matter of slight adjustments to accommodate this—tweaking the settings on the program's Compatibility Tab should solve most issues. However, certain programs stand out for their seamless operation on Microsoft's newest operating system (at least based on our experience with the Windows 8 Consumer Preview).