People that have travelled here warned us about pickpockets; the guidebooks all warned us about pickpockets, every public place, including the subway and all of the popular tourist sites have plenty of signs warning about pickpockets.
We were vigilant about only carrying as much cash as we thought we would need for the day, and leaving the rest along with our passports locked in the hotel safe. Even at that, Bryce wears a money belt, and I have a little magnetic wallet that clips onto the inside waistband of my pants and is covered by my shirt. Nevertheless, I always held onto my purse which contained my iPad and camera, as it was hung across my shoulder. Bryce and I were always careful to back up against the wall in crowded elevators.
While we were accosted several times a day by people asking "Do you speak english?" we went against our normal inclination to be friendly and helpful, and just kept right on walking, ignoring their overtures. It's hard to say if these were ploys or not, but other than that, we did not experience one moment where we felt any threat of being robbed. We also did not hear of this happening to anyone else. Hopefully we will find this to be true in Spain as well.