Font rendering is horribly, horribly broken in Windows 8. Like, shockingly bad.
Since today is the first day the RTM has been made available to MSDN subscribers, there's no good information available about it online either. There are plenty of threads where people complained about the issue in the preview release but those were all dismissed with "it's not the final version". Now we have the final version and it's terrible.
The funny thing is, I was having a problem with font-rendering in Chrome on Windows as well. For some reason, Chrome renders fonts properly on Macs and it renders fonts properly on Linux but in Windows, Chrome has some weird issue where anti-aliasing is broken. If you're running Windows 7 and have IE9 and Chrome installed, take a look at the following page:
http://www.google.com/webfonts/specimen/Play
In IE9, the fonts are rendered perfectly smooth. In Chrome, it's all jagged like there's no antialiasing being applied at all.
On Windows 8, Chrome looks pretty much the same as it does on Windows 7 but everything else on Windows 8 looks even worse. IE10's font rendering is worse than Chrome. It's like the entire OS is ignoring the ClearType settings.