It pretty much requires you to use the babel&#x2F;crisper&#x2F;vulcanize toolchain, which in my limited experience doesn&#x27;t do nearly a good a job of minifying Javascript than other tools (because it can&#x27;t do symbol renaming). I haven&#x27;t found a way to use browserify with web components, for example, so no ES6 modules.<p>Polymer is made of magic. It uses magic cutting-edge browser features where available, and where they aren&#x27;t it fakes them using magic. Some of its APIs like Polymer.dom(x) are completely magic. When it works, it works really well. When it doesn&#x27;t you are going to waste so much time trying to find out why.<p>It also assumes that everything you&#x27;re doing is through Polymer; so you won&#x27;t get much mileage out of, say, JQuery. While it admits the existence of other Javascript libraries it tends to blank them at parties.<p>If I were to do my current project again... I&#x27;d probably still choose Polymer, although I&#x27;d take another look at the other Javascript UI toolkits. Web components are so, so nice for designing UIs --- I can finally use actual computer science techniques like abstraction and modularity for building UIs! --- and it&#x27;s got the best consistent look and feel that I&#x27;ve ever seen in a Javascript UI toolkit.