I started using GKE at a seed stage company in 2017. It's still going fine today. I had zero ops experience and I found it rather intuitive. We brought in istio for mtls and outbound traffic policies and that worked pretty well too. I can only remember one fairly stressful outage caused by the control plane but it ended up remedying itself. I would certainly only use a managed k8s.

So I guess I'm a fan. I use a monolith for most of my stuff if I have the choice, but if I'm working somewhere or on something where I have to manage a bunch of services I'm most certainly going to reach for k8s.