AWS often releases features very early, to satisfy the first tranches of early adopters before rounding out the feature with feedback from these passionate users.
AWS EKS is a good example for anyone who has had a play already.
Nearly everything.
Old k8s version. No upgrade possible. Odd deployment process (not fully automated). Support is unable to help in a timely manner. First deployed cluster was directly broken (no DNS resolution).
We eyed on switching from kops to EKS. But immediately stepped down after experiencing so many issues.
AWS EKS is a good example for anyone who has had a play already.