How Google sets Goals : OKRs. Have you tried this in your org?

OKRs stands for Objectives & Key Results what will be set on quarterly basis and are applicable for each and every individual in the company. It was first implemented in Google and later in major tech startups. Here is a video which talks about OKR in depth.

I believe that’s a great process that ensure the startups can track, measure and improve what they want to achieve at an individual level. However, I think some of the methods / guidelines needs to be tweaked a bit based on the state of the company, industry etc.
Has anyone here (founders / product managers) implemented (or tried) OKRs in your organisation? What challenges did you face? Would have to have a healthy discussion with some actionable items.