OK, I will chime in. I am an IT guy and am not concerned with Windows 10. I have been using it for quite a while, as I was part of the tech preview and beta process. The first few versions we got were not that great, but the last 2 or 3 were flawless for me. I have not used to latest version yet, but I am sure it is as stable as the last few I used. All of my programs seemed to work without issues. We also use custom software at our office and that worked without any problems. I have NOT used Windows 10 on a tablet yet, so I can't say for sure how that will work out. I do have a MS Surface Pro running 8.1 and would be willing to give 10 a try. I just need to take the time to make it happen.
As with any update, make a complete system backup (and test it!!!) before upgrading.