One thing that has been frustrating me in learning the MEAN stack has been how to extend the basic Article example (or a CRUD created module) beyond the basic data model. While you're trying to learn AngularJS and Mongoose/MongoDB interactions, you can find lots of literature on modelling, but little on how to modify your core CRUD views, model and controllers to work together. I'm sure that there may/are better and more elegant ways to accomplish this.