Debates on philosophy, atheism, religion, science, progress, politics and social standing that were raging in Russia at the time were threaded into the story with the subtlety of a great craftsman. There were so many "Aha!" moments that randomly popped up and then fluttered away in a couple paragraphs. Unlike Dostoevsky, who expounded on his philosophies deliberately and with detail Tolstoy never forces an argument down your throat. This book, at it's heart, is about the characters and only about the characters. You just feel a bit smarter and ask a few more questions about life as you go along reading.
I know you're thinking "sure Christopher, that sounds all well and good but when I read, I read for pleasure. Anna Karenina is 800 pages long and it's so old, it sounds like it'd be terribly dry and hard to follow." I was as skeptical as you! I'm not trying to trick you because I think it'll make the world a better place. I read War and Peace (which I loved in different ways) last summer and it took me 3 months. I finished Anna Karenina in 3 weeks. I couldn't put the thing down. Tolstoy creates memorable, complicated characters that face, in many ways, the same problems we still face today. The language is simple, straightforward and easy to read.
Give it an honest shot, if you don't enjoy it I'll write a blog dedicated to you and you're awesomeness and of me and my lameness.