I bought this to replace an old radio/cassette in my other half's VW Polo, because she likes to have music available in the car, and wanted something she could plug her mp3 player into.
Fitting was straightforward (although getting the old unit out was very tricky!), and it was easy to set up.
After using it for a while, she's discovered she prefers to use a 16Gb mini flash drive ([...]) charged with mp3s.
The only potential worry is the advice not to start the car with the device set to USB input, because of potential damage to the USB device. However, on the only occasion she forgot to reset the unit, it displayed a "checking" message, and carried on working.
All in all, a worthwhile buy, and good value.