Entity Systems have fascinated me for a while, the idea of being able to effectively turn anything into anything else with a few removals and additions of components makes me happy. My knowledge on the Entity System and it’s pros and cons is somewhat limited. So if you want to find out more read these posts (from far more knowledgable others) :
PART 1: Small Beginnings – Introduces the Renderable and Transform components.
PART 2: Flying Around – Introduces the Physics and Player components.
PART 3: Crashing Into Things – Introduces the Bounds component.