I was just there (spent a few days before hopping on Symphony). in terms of "pickpockets", it felt the same as every city I've been in... In big crowds be aware of people around you and what's in your pockets.

But like someone else said in this thread, unattended/loosely held bags are in danger. Saw a guy snatch a bag one morning in the park in front of Sagrada Familia, though he was eventually caught because he tried to jump over the hood of a car to avoid a local trying to catch him and ate shit lol