OK, this probably doesn't apply to violent crime, but petty crime like pickpocketing, etc. There is basically no point in reporting it. The police will do nothing. I live in Barcelona, and there is a lot of this stuff goes on (I had my wallet stolen once, lots of tourists get robbed). I went to the police when my friends camera was stolen. Did anything happen after? No. Yet I have been stopped 5 times for my cycling behavior (going through red lights on a quite road usually).