I quite like Prince Andrei in this one, I actually don't know this actor and have never seen him in anything before (but I barely watched anything in the last five years just because had no time, and War and Peace is the only thing I watch on telly/iplayer now, actually I don't know ANY actors in W&P except Jim Broadbent and Gillian whathername, Countess Scherer).
By the way, again they changed a lot in characters/looks, Count Vasily is languid in the book(like his daughter), in the film he is far more weasel-like, like his children(in the film). Also he has another son in the book, which is quite funny (funny to read about, not funny by himself).
Anyway, Andrei is less hot in the book, because even though he is described as quite good looking, Tolstoy constantly emphasised that he was short. He often used phrases like Andrei 'was rubbing his small hands' etc 
Anatole yeah, as I said, is supposed to be far more handsome in the conventional sense, but I agree that there is something sexy about the actor, though also agree that he smirks too much and lacks magnetism compared to what he should have been.
I do think Lily James was believable enough as a girl who fell for him madly(and I liked the way she told Maria that she was ending the engagement), I also really like the actress and the portrayal of Sonya.
Oh, by the way, in Russian Rostov is pronounced with emphasis on second -o-, RostOv, why on earth do they insist on saying ROstov?
Natasha is RostOva, because adding the 'a' on the end turns the surname grammatically feminine. In most Russian in origin surnames the woman's version of the family name would have an 'a' or 'ya' on the end.