We did have some issues at the beginning, mostly due to Elixir and/or Phoenix still being in the process of maturing, like the fact that Phoenix Contexts were introduced (which required some big refactors) or the deprecating of Models in favour of Schemas.Another pain point at the beginning was no clear way of creating and deploying releases. We tried Edeliver for a while and ended up bringing more problems than solutions, so we ended up using dockerized deployments and are happy with it.