Feathers makes extensive use of modules (which are called Feathers services). These services work like ExpressJS middleware and can be used with app.use('/path', serviceObject). Services help developers keep their applications modular and as minimal as possible, without any unnecessary l...
Since Feathers itself is built on top of Express (it's a thin wrapper over socket.io, primus and Express) and because of Feathers' highly modular nature, it's very easy to integrate Feathers in an existing Express project.
Although the documentation for Feathers is very good, it still needs some configuration in order to get Feathers up for developing something with it. That said, the learning curve is considerably reduced if you are already experienced with ExpressJS.
Being built from two of the oldest Node libraries where each of them has had several releases and constant bug fixes and patches means that express.io is a rather mature solution for building realtime web applications.
Not only express, but every Node framework has this problem. While there exist plugins and libraries that allow developers to use relational databases in their web applications, they are not very good and usually it's a hassle and more trouble than it's worth to use a relational database w...
Because of the MVC architecture with which Sails apps are created, you'll find the task of separating the business logic from the user interface and keeping the interactions between them in a separate layer, extremely easy.
One of the major benefits that Sails has is performance. But it's not as efficient when starting up. sails lift takes quite a lot of time to execute completely (although it is doing a lot of things behind the scenes - if you run it with the --verbose option, you can see all the different things
The Waterline ORM is a bit limited. Associations were finally added after much time and many requests. However, they are (as of 2015) still incomplete. It is not a great ORM for MongoDB. You will very likely be using native MongoDB queries throughout your code more than you might like (for example,