1/ France had Madame Bovary, Russia had Anna Karenina, Germany had Effi Briest.
However, if Flaubert dissects his Emma and contemptuously puts on display all of her sentimentalism, shallowness and philistinism, and Tolstoy can now and then be harsh towards his Anna, Theodor Fontane openly loves his heroine. Effi therefore is a lot more likeable, even lovable. Anna and Emma we can see clearly, thoroughly, but they're characters that evoke lots of strong emotions, characters that readers, at least I, have to struggle with, on a personal level. With Effi, it's different. Fontane writes of her innocence and rich imagination, of her vivacity and love of life, of her free spirit, and above all, of her youth- she's still a half-child; then he writes of her loneliness, fear, doubt, and pain, making us love her and care for her as though for a real person.
2/ Effi Briest is a rather well-rounded character. However, like Emma at Bookaroundthecorner and Himadri/ Argumentativeoldgit, I have a problem with the novel: Fontane always refrains and leaves things unwritten. Not all writers spell out everything. Jane Austen writes enough. Flaubert keeps it subtle. Henry James prefers to hint, and suggest. I myself have praised Henry James's subtlety: the jumps in The Portrait of a Lady (and 2nd post) and the things that are left unsaid, as well as defending the ellipses in the novel as not simply "disguising a deficiency". But Fontane refrains too much. It's not just that the sex in Effi Briest isn't described, which is fine (even if the 1st time the affair's consummated is easy to miss), but the whole affair isn't there, and most importantly, Fontane keeps Effi at arm's length instead of bringing her close to the readers and entering her mind, and except for a few small observations now and then such as Effi blushing when Crampas appears or her husband vaguely noticing something different or Effi overreacting to Roswitha's familiarity with Kruse, he withholds from us her thoughts and feelings. That reduces the emotional impact.
At the moment, I'm on chapter 21, when Innstetten has just been promoted and Effi's about to go to Berlin to find an apartment. Hopefully Fontane would describe more once her life takes a tragic turn.