I never used the SD card reader and key USD, I spend most of the time via Bluetooth to play music which in particular maintain navigation in the playlist (via the remote install on the steering wheel for example).
Two regrets:
- There is no possibility via remote controls and on the product to pass the song accelerated
- The cable jack to plug works very badly and is very poor. It seems that such a sound in mono as well. Fortunately there is the Bluetooth (iPhone 3GS and 2nd generation iPod touch in my case).
I recommend this product.