Pawel just ended the first of his three presentations today, a webinar covering FireMonkey and particularly focused on styles (was very good, despite some audio issue at the beginning). There are two more sessions scheduled for later you can join, and the recording will also become available.
I wrote a "companion" white paper for the webinar, available online. It is a 30 pages technical introductions to styles and components architecture in FireMonkey. It was originally written for previous versions of the library, but the core concepts of styles still apply and I did update it explaining the differences.
Webinar information and paper download at the event web site:
http://www.embarcadero.com/rad-in-action/firemonkey-multi-device