The book was so different than the tv show, I can hardly explain. I would say Sara was featured equally with the rest of the cast. The book was actually narrated by Stevie, and he was almost non-existent in the show. I enjoyed the show for what it was, but only after letting go of my expectations of what was going to happen and enjoying the new plot as it was.
I can't forgive them for killing off Marcus, though. :( And yes, Rosie McEwen was amazing.