Review on Polymer by Marcelo Montalvo

It's easy to use, powerful features with good documentation. The project has been under active development since 2010 so it comes with many useful plugins that are not available in other libraries like Angular or ReactJS (or any of its competitors). I'm currently working at my own startup where we're developing our first product built entirely from scratch using polymer components. So far everything went smoothly but there were some issues when integrating third party modules into our application which required additional workarounds. But overall experience was great! We used all different types of elements such as buttons, forms etc., they worked flawlessly without problems even if you didn't have much knowledge about HTML/CSS.