Using the upgrade feature from https://www.microsoft.com/en-us/software-download/windows10ISO I updated my SP3. Created an ISO and installed fresh copy on my main laptop. Both are working perfectly, Now doing a clean install on my SP3. Will do a clean install on my other laptop and HTPC sometime later.
Sounds good to me. I've a win 7 pro license sat waiting to get taken back home with me and installed on my main computer
Reading the threads on this forum alone, it seems that half the new 10 users actually have a problem, and then other half are just crying because Microsoft somehow had the audacity to change something. It reads like these people expected windows 10 to just be windows 8 with a different number..