Flux on the other hand was hard to grasp, since all of the different implementations and the naming problems. Actions in MVC are just methods of the controller classes, but in Flux they are objects, which kinda threw me off track right in the beginning.
Also, I came from ExtJS and Ember and was accustomed to two-way data binding and the whole Flux thing felt backwards, because interacting with the Models in Ember-Data didn't take any effort. After they were bound I just needed to type my data and they get updated automatically. I just had to look about gathering them at the end and send their updates to the server.