Any kind of git-ops style deployment was out.
ECS merges “AWS config” and “app/deployment config together” so it was difficult to separate “what should go in TF, and what is a runtime app configuration. In comparison this is basically trivial ootb with K8s.
I personally found a lot of the moving parts and names needlessly confusing. Tasks e.g. were not your equivalent to “Deployment”.
Want to just deploy something like Prometheus Agent? Well, too bad, the networking doesn’t work the same, so here’s some overly complicated guide where you have to deploy some extra stuff which will no doubt not work right the first dozen times you try. Admittedly, Prom can be a right pain to manage, but the fact that ECS makes you do _extra_ work on top of an already fiddly piece of software left a bad taste in my mouth.
I think ECS get a lot of airtime because of Fargate, but you can use Fargate on K8s these days, or, if you can afford the small increase in initial setup complexity, you can just have Fargates less-expensive, less-restrictive, better sibling: Karpenter on Spot instances.