Not addressing any potential privacy/security concerns but as far as daily operations, I've had it on my primary desktop workstation, my higher-end laptop, my girlfriend's budget laptop, and my work Surface Pro 1. Haven't noticed any slowdowns or lockups. If anything it's on par or a little faster than 8.1. I had a minor issue on my laptop at launch because it kept trying to install the wrong touchpad driver but I used the little "hide updates" app they provide and that sorted it until the underlying issue with Windows Update was addressed and it stopped trying to pull the wrong driver after a few days.
I use 10 at home, works perfect. Some people have issues with GPU driver support (old Nvidia card in my bro's case), and 100% cpu issue, also sounded like driver/software related.
I wouldn't update on a work machine however - no need to put your time at risk.
Self-employed, so my "work" machine is mine. Might as well bite the bullet and get the upgrade done.