It works differently for different people. For me it helps drown out background noise in the office and helps relax me so I can get in the zone. Its important to note that I play my music very low with headphone and with rather no lyrics or lyrics in a different language so that it doesn't distract me.

With all that said though, there is nothing worse than being subjected to a coworker's music choice. Having experienced this at different jobs, I can totally understand why other people avoid music at work like the plague.