Before you all ask, yes it's battery powered (it claims 10 hours, though you may want to plug it in for prolonged sessions), and yes it supports Bluetooth 4.0, aptX, AAC, SBC and all that other goodness. We tested it out (incidentally) on a Bluetooth speaker of our own, and it does exactly what it claims. We hooked up a few phones, and were able to battle it out for the airwaves. You can't get multiple tracks running over each other, so if you were having visions of fierce DJ sets, then sadly no dice. You can, however, engage in some "tune fi tune" style selecta sessions. There are three LEDs along the bottom edge of the 3play that let you know how many devices are connected, and playing media on any one of those will barge the currently playing song out of the way, and take center stage.
The reality is that it doesn't always work that smoothly, with the result being sometimes, confusingly, pausing the music on one phone causes the other to start, as if the play/stop signals have gotten themselves in a bit of a twist. Essentially, though, it does this core task pretty well, and if this is solving a problem that you have, you'll be more than happy to overlook this minor bug.
What we really like about the 3play is its potential for other use cases. We know it's not unique to this device, but by thinking of the 3play as a Bluetooth dongle (or a virtual cable from your phone's audio out), you can get creative with it. For example, we hooked it up to the 3.5mm microphone connection on our DSLR, played music through the phone while we recorded video, and hey presto -- quick and dirty wireless video soundtracks. In fact, there's a bunch of different ways you could use this that go beyond its basic reason for being. That's a good thing, too, as at $99 (though you can find it for a bit less if you look around), it's not exactly the cheapest widget on the market. But, it is one that will likely appeal to a very particular audience. We just wonder if it was a conscious branding decision not to offer a four-device version?