Was on a mates stag do there one time, this bloke lifted my phone out of my pocket. Didn't notice at all, was like a magic trick or something. I then spotted it in his hand so he gave it back, was so impressed by his technique I didn't even think to consider biffing the bloke! Wasn't on Ramblas, this was over towards Barcelonetta. Near a pub called The Fastnet, far side of the harbour. ****ers are everywhere on Ramblas though for sure, steer clear. There used to be a pretend Ronaldinho did a show on Ramblas. Was unbelievably good with the tekkers!
Been to Barca a few times, never had a problem with pickpockets personally but I know of people who have had, so wear a money belt if you have one.
Try El Glop on Gracia if you're up there. Cracking little bar with great tapas. A good fish restaurant at the harbour is La Gavina. Went there and had sea bass after the 99 final. Well, a day or so after, not immediately after.
Park Guell is lovely, Barca is great if you like a bit of art and architecture, went a few years back and loved the place.