I've written a not so short article on Unity's implementation of an Entity Component System (ECS) model & Data Oriented Design (DoD). No pre existing knowledge about ECS or DoD is required by the reader.
The article handles the principles of ECS, DoD, contains a small custom documentation about the fundamental concepts of Unity's ECS as well as a start guide, where I show the reader how to rewrite a tiny game in ECS fashion.
Lastly, I've added a critical comment on Unity, discussing their work & claims.
Of course, this is a lot of input. You can jump through the article as you wish.
You can find the article as well as the Unity project on my GitHub profile