Windows 8 is not without hiccups, especially with Boot Camp / Apple hardware.
I needed a nonWindows program for burning DVDs, such as Mac OS X's Disk Utility. For some reason, Windows fails at burning ISOs correctly (and failed to do so for Windows 7, and for Windows Vista).
Update: Installing the Boot Camp 4.0 drivers helps fix a lot of problems.
Boot Camp drivers mostly work, though trackpad functionality was completely absent in Windows 8--you'll have to temporarily plug in an external USB mouse so that you can fix the trackpad drivers.
My MacBook Pro keyboard also fails to work exactly every-other-boot, and whenever my physical keyboard fails, strangely so does the On-Screen Keyboard. To work around this, simply reboot by holding down the power button. The next boot always works.
Google Chrome and Noogra Nuts completely freeze up my Windows 8, so you'll want to save often and consider using alternative software.
The first ten times I tried to open Maps, it stuck at the purple loading screen.
Other than these strange bugs, Windows 8 runs quite smoothly overall. I really like the new Start menu and Metro apps. Microsoft clearly gets how important social software is these days, offering built-in apps for IM, email, news, and the free SkyDrive cloud service. And finally there's a standard way to search for, download, install, and update Windows software: the Windows Store.
Windows 8 is not ready for public use, especially for Boot Camp / Mac users. But if you've got the technical skills and perseverance to break and then slowly fix your computer, I think it's worth it.