A rundown on Win10 issues I'm seeing people talk about:
- Install can fail forcing you to either back out or do a clean install. This seems to be infrequent, but back up your stuff before attempting the upgrade.
- Some third-party driver issues, generally with older or obscure sound/video cards. Consider updating all drivers before attempting upgrade.
- Problems with computer sleep settings. It's possible that Wake on LAN is getting triggered more often. This is draining some laptop batteries as a result.
- Microsoft has apparently decided to use a torrent-like model to distribute software updates, and your new Win10 machine will be set to serve updates by default. Consider turning this off especially if your network provider charges by the byte or caps your uploads.
- Font smoothing complaints with Edge. (Of course it's not like IE was any better at this.)
- The Win10 upgrade process will encourage you to join the computer with your Microsoft account. You then log into the machine with your Microsoft account, not any local account.
- Lastly, BACK UP YOUR STUFF BEFORE THE UPGRADE.
Some teething troubles to be sure, but so far this rollout is going splendidly all things considered.