Interference from radio reception I could not fetsstellen date.
The blue LED located at my car is not in direct view and I find it enjoyable to see whether the connected devices are powered.
In a pinch ... a tape over it stick :)
Processing? Ok for the price.
In my opinion is the weakest link is always the "cigarette lighter" so the 12 volt power socket.
This is an ancient and very shaky standard.
I tested the Mumbi with LG and Google smartphone, two older Samsung phones and a Sony mp3 player.
Everything works perfectly.
Because of the price: 5 points!