There's a learning curve, and new features are being added, but at this point I would not hesitate to recommend Kubernetes to just about anyone.
CI: We standardize on CircleCI and it gets the job done, but has some serious shortcomings. I've also come close to building my own on top of the k8s cluster and it's not the correct time investment for me right now, but I'd consider building my own in the future. I've yet to find a CI framework I really like.