I had to send Mjoll to the blades to get her to shut the f up. If I could find a way to have her as a follower w/o the annoying dialog foaming from her mouth I'd bring her back. She is to steal a DA2 quote a woman shaped battering ram. Give her some heavy armor and a massive axe and just get out of the way.
But I can't tolerate her damned dialog.
No kidding... Right now she's following [my level 52 fighter] and I want to just turn to her and say, "Do you realize how easy it was for me to get your stupid sword back? And you almost died in there? And you were saved by some freaky little introvert who probably isn't attracted to you anyway because he's... er... um... attracted to other people? Don't you think you may be embellishing on your glorious past a bit? Now shut the hell up!"
By the way, I lost a follower that I actually liked (that mage that you can find in the Riften pub) in the Dwemer ruins looking for her stupid sword. His dialogue was a bit annoying too, but much more acceptable than hers.