[ffreire]

I think you're confounding Polymer with Paper. The core Polymer elements that have currently been released make no assumption as to your UI preference, which means you can style them individually as you please.

I've been creating my own Polymer elements for an internal project and have been pleased with the result so far. We've got some particular branding requirements that I've been able to reproduce to great effect. I think as long as you stay away from the messy parts of Polymer (such as making XHR requests in the DOM) then you may find the experience more agreeable.