We saw this movie last night and enjoyed it enormously. It's quite funny at the start and gets much more serious in the second half, with a sweet and moving conclusion — which you would think would be hard to do, given that the world is ending. Steve Carrell's role is mostly serious. He does a fine job, especially in the most serious, subtle moments. He really is an excellent dramatic actor. Keira Knightley is not annoying for a change. She shows that she can be an adequate actress when she chooses to be.
Speaking of KK, one of the previews shown before the movie was for an upcoming version of Anna Karenina, starring KK as AK. It looks like the movie makers have managed to convert a mediocre and silly novel into pretentious twaddle.