I have rolled two Windows 8 machines up to Windows 10. The most drama free upgrade in my long windows life. Only thing I can suggest is watch for your anti virus support immediately after the launch. I would check with your own antivirus company about compatibility before making the switch.
Here are some links that I have been asked to inform readers about. If you click on them, you will get me some credits with the people that decide my MVP award
Many Windows 10 Related Videos at the MS Channel9 site
Developing in Windows 10
Starting with Windows 10 Development
Windows 10 Development in the Microsoft Virtual Acadamy
Enterprise support for Windows Edge and Internet Explorer 11
The Azure September virtual conference