One of the best novels out there; If you want to know how to write a good book, take a serious look at Eliot's masterpiece. She has an amazing ability to do two things:
1) the characters drive the plot, not the other way around (Rowling?). Everything that happens in the book is a direct result of a BELIEVABLE action by one or several of the characters, considering their individual personalities and quirks. The novel progresses because the characters force it to.
2) somehow Eliot makes it difficult to hate the antagonists in the novel. Everyone, even the characters we WANT to hate, has some sort of sympathetic motive--something that we all can identify with (insecurity, selfishness, pride, etc). No one is 100% evil, unlike many villains in lesser novels.