1) The large patch issued for 8 on October 11 [KB 2756872] restores compatibility with Office 2003. Previously Office 2003 partially broke 'Windows Update' on Windows 8 RTM.

2) Font rendering in Office 2013 Preview on Windows 8 RTM was atrocious, even with 'Acceleration' & 'Sub-pixel positioning' turned off. This defect appeared to persist with Office 2013 RTM.

After working in Office for several days I found the situation unacceptable and concluded that the Office team simply could not have let a defect of this magnitude pass through to the final release (let's stipulate much in the interface design of 2013, especially the 3 themes + icon spacing & customization are lamentable).

And so it was: re-running 8's 'ClearType Tuner' completely resolves earlier rendering issues. Even IE 9 (Desktop browser) in 8 appears to benefit.

It may be worth mentioning that re-running 8's 'ClearType Tuner' followed installation of the latest AMD Catalyst [12/10] for my video card.

Good wishes.