Polymer is moving from Bower to npm.
FINALLY. Having everything in npm is great :)
We're switching to using ES6 modules instead of HTML Imports.
Sad to hear that. HTML Imports would be the right way to go for HTML templating. However, that technology has been a pain for a long time, because of the lack of support (not because it's bad!) So that move actually makes sense and is a plus for the time being. The problem of supporting old browsers remains, though, and afaik there is no way to polyfill ES6 modules. They will have to be transpiled :(
Well, at least Google knows what they are doing:
The one HTML Imports feature obviously missing from ES6 modules is native loading and parsing of imported HTML. We’d like to see the platform get this feature back [..]
So they will probably wait for HTML Imports to get better support (or for the W3C to release the succeeding standard, which hopefully gets more love) and go back (away from ES6 modules). JS is not the right place for things like HTML and CSS and there is a reason why they are separated.
All in all, the mentioned changes are definitely reason enough to check out Polymer for productive usage, if the target audience likely has up2date browsers.