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.