I like that it's easy to use, but also powerful enough if you need more control over your code (like adding custom elements). There are some things missing from this framework which have been implemented in other frameworks such as React or AngularJS - epecially when working with forms! It could be better organized though; maybe creating modules would help? The biggest problem we had while developing our application was how hard everything became once there were many components involved at one time since they all required their own libraries/frameworks etc.. This solved most of those problems by allowing us only include what needed instead having too much overhead included everywhere just because someone thought so back then :) We used polymer mainly due its simplicity & powerfullness together wich makes development faster than any others i've seen before even angularjs itself!