If you know me, you know how convinced I am that Web Components is the future of how we build components in the browser; not React, not Angular, and not Vue. With that said, Polymer is just one vision of how we can fill in the various parts of Web Components and make them easier to build. But it's a good one and I've used it myself successfully in a couple of projects now.
Hands-on with the Polymer 3.0 preview - You'll definitely want to pay attention to this one whether you read the one above or not. Otherwise you won't have a lot of getting started information. The two blog articles mainly talk about the whys and what has changed over time.