Never used one, but in my opinion they are way overpriced. Take a look at a radio with similar features that is a normal shape. It will be about $30. As opposed to the $250-$350 they want for one of those things. They should play MP3's and have an external USB port, accept XM/Sirius signal for that price. Yet they don't. And as such, they are a ripoff. Just my 2 cents.