Yes the cops will come over and tell them to shut the **** up. I had that problem a few months ago with some neighbors beside us that still live there. It was about 5 am, and they were playing their music SO loud, that someone from 4 floors up came down to tell them to shut up. The walls of my apartment were shaking from the music.
Now, I could care less about loud music as I play mine loud too, but during the day, not 5 am when I have work and school coming up. So, I went over to their apartment myself, knocked on the door, no answer. I waited 15 minutes, nothing changed so I went back, kicked their door as hard as I could and heard some ***** inside yell "I'm not answering that ****ing door". So, there's a crack in the bottom of the doors, I bent down and yelled into it as loud as I could that they had 5 minutes to turn their **** off, or the cops would be the next ones knocking on their door.
We're now at 6 am, and the music is louder than ever. I called the cops and it takes them 45 minutes to show up. It's now 6:45, roughly, and the music has been turned off for about 15 minutes or so. Although you can still hear the ****ers on their balcony yelling at the top of their lungs. When the cops show up, I am standing in the hallway waiting for them. They hear that there is no music and one of them says "You know you can actually call and cancel right?" to which I reply "Yeah well you know you can take less than almost an hour next time right? Or how about this... " Opening my apartment door, I let them hear the yelling off their balcony to which the cop nods and tells me to shut my door.
THe next thing I know I heard something louder than their music on their front door. The next thing I know I hear the cops blasting them and so on and so forth.
Their music has never been loud since. That was 5 months ago roughly. So I would say, yes, it is worth it.