I haven't read all Jodi Picoult's books - but have read three in the past year or so: My Sister's Keeper, 19 Minutes, and Handle with Care.
There were similarities in all of these books (and I assume in many more of her books as well), including:
point of view: Picoult tells the story from the perpective of various characters, devoting different chapters to be told by someone different. In this way, the reader gets a somewhat broader idea of the big picture - but everything is still biased and details are left out. It's actually pretty cool - once I got used to it. By doing this she is successful in allowing us to really know the characters, but she still maintains suspense.
theme: each of these books has a plot element of a lawyer/crime/court scene. In this way she seems to be constantly developing a theme of justice in some way. These books also dealt with some sort of sickness, disease, or other medical issue. *They all had a tragic ending - be prepared to cry.
circular style: I guess this is similar to the way she uses point-of-view - rather than telling her stories from beginning to end, chronologically, she tells them from so many perspectives (character's as well as time-perspectives) that throughout reading there is a piecing together of everything that usually is complete by the end of the book. Again, a thought provoking approach to writing (adding suspense). With all three of these books I was hooked from the very beginning simply because so many questions are posed right away that demand answers. Even when the story itself wasn't really a subject I typically enjoy (such as crime/thriller) - I couldn't help wanting to know the end of the book.