I run a firespinning troupe. When you're practicing routines, you HAVE to have loud, clear music, because the fire tools are spinning quickly, causing a massive amount of air turbulence with the flames, creating a very, very loud roar.
In order to practice a routine with perhaps five other people on stage, you have to be able to hear the music to know where you are in the routine - otherwise someone might move too early or not move, and, well... bad things would happen.
When I founded the club, I was looking at all sorts of options; what I really wanted was a shop boombox, but they were expensive and didn't have the battery life I needed for practice... and couldn't be plugged in because you practice outside.
After reading a lot of reviews, I got the UE boombox. It has several features that were incredibly useful to me - most notable the fact that it could store three bluetooth profiles AND connect through a normal 3.5mm jack - that way we didn't have to just use my music collection, but could use other members' as well without them having to mail me the files.
Solutions we tried to use before was an iHome system, which didn't come close to having enough volume, and an old CD boombox... which worked fine, except the CDs got worn out pretty quickly as they were outdoors, and it was limiting on what music we could use - we had to have it beforehand.
So I got this UE boombox, and it was perfect. It doesn't have THE sharpest sound in the world, but it doesn't have distortion with everything turned to max volume, and it has solid base (so you can hear the beat clearly) and good battery life.
For anything requiring outdoor music that has to carry well or be particularly well, I highly, highly recommend the UE Boombox. (It would work perfectly for, say, a beach party, or something like that.)