Anything I should know before upgrading to Windows 8.1?

I had two upgrades on win 8.1:
1) one on bootcamp, and the overall system went a bit slower than as a clean install
2) one on another PC, and I got artifacts of text rendering.

Version-wise it wouldn't be a problem, more is about the upgrading process which isn't so good as a clean install. If you can, do a reinstall, it will save you of many future possible problems

 

There won't be too much trouble updating through the MS "App Store." I did it this way, but it was with a fairly clean installation of Windows 8. You won't need to reinstall Apple's Windows support software. However, I would strongly suggest uninstalling your graphics drivers before updating to 8.1. I had a set of AMD Catalyst GPU drivers installed at the time I changed to 8.1 and it caused a few issues. Reverting to the drivers Microsoft provides with Windows 8 saved those headaches. After getting 8.1 up and running, I reinstalled the set from AMD and have been OK ever since.

As far as games, 8.1 introduced a bug that will cause mouse lag for certain titles. They released a patch that you have to download separately. It doesn't fix all games, but they did release directions on how to apply the fix manually so if you have a game that's not covered by the update, you won't be stuck. Do a search for "Windows 8.1 mouse lag fix" and one of the links will take you to appropriate MS knowledge base article where you can download the update.