It's unclear from the article whether the Pope's Twitter feed was swamped with abuse, of which three or four examples are given here, or whether the abusive tweets were nothing more than isolated, sporadic examples in a sea of favorable comments but singled out and highlighted by the Mirror in typical, tabloid, sensationalist style.
https://www.google.com.bz/#q=pope+twitter+abuse
And --- I just glanced at it ---- it looks like it's been a lot more widely covered internationally than just The Mirror (although maybe they're all just referencing the Mirror article, I don't know.)