I've noticed that the writing on PP isn't as good as on Grey's Anatomy, though Shonda Rhimes is their mutual creator. The characters seem to have ADD, defending their actions arbitrarily, then taking a high moral ground about another character's incredibly unethical behavior. The whole show dissolves into a collection of self-righteous rants or explosive speeches, each lasting 30 seconds or less. As I've begun to watch season 4, I notice there's not much character or relationship building. I don't know anything about these characters (as opposed to GA) other than that they'll do whatever they want and rationalize it away in a second.
I miss Dell -- he was refreshing. The little-sister Shephard is scary, her energy is skittish and dangerous, like she's likely to kill someone on the operating table. Intentionally. I don't plan to borrow any more seasons. Stick with Grey's Anatomy.