Well, for me Arimidex was so very horrible, I barely lasted three days on it. I was in an almost catatonic state of depression two hours after I took the first dose, and then got just about every other bad side effect soon after.
Femara, in comparison, relative to the other, was not so bad at all and I lasted almost thirty days.
But not every woman has the same problems, or any at all. Many though do have some problems.