Some description can be read in my old topic:
but this is already a bit outdated...
The mod significantly changes the gameplay, so, creating a list of features or differences - can be a fundamentally wrong thing.
Basically, the essence of the mod will be clear to those people who played in A12 or earlier, and who were disappointed by modern changes.
The usual style of playing modern vanilla will not work here for sure. The mod is very complex for the initial understanding and therefore will immediately alienate those who do not like to understand.