On the plus side, the Soundfly AUX plays static free. It also sounds good enough that after a few minutes I'd forgotten I was listening through a device broadcasting through the radio.
It's also pretty simple to operate.
On the minus side, I'm flustered by how this unit sorts its songs. I'm not sure of how the unit decides the order to play the songs in, but it's not like my pocket-sized mp3 player, or like the mp3 player on my computer. If you feed a folder of songs to the unit, and they're numbered 01, 02, 03, etc, the AUX might or might not play them in that order. I've never seen another player do that before. The Soundfly AUX doesn't play the songs in alphabetical order, either. (And no, I didn't have the unit set to shuffle.)
Another thing bothers me about the AUX. Let's say that you're driving and you turn off the Soundly using its power button. You'll naturally hear static coming through the radio, since the AUX is no longer broadcasting, so you turn off the radio, too. So far so good. You reach your destination and turn off the engine, but the next time you turn on your ignition, the Soundfly AUX will power on with it and automatically start playing music, even though your radio might still be off. This can be irritating. I think this the first product I've ever seen that would switch itself back on spontaneously.
While these irritants didn't make me send the unit back, they're two major drawbacks that I think consumers should be aware of.