I had an Acura RL and the iPod interface was lousy. On the Volt it's very straightforward. However, I had a hard time getting it to work reliably with my 64G Nano so I just bought a micro USB drive. It's way easier to store and the Volt indexes everything quickly. Since the drive is just folders and songs there's not any duplication of functions.
I've thought for several years that the best way to go these days is to just use flash. The player just duplicates what the car does and generally gets in the way. FWIW the Bose sound system in the Volt is pretty darn good. Definitely better than the Bose system in the RL. Part of that may be the Volt is more quiet. After we got the Volt my wife mentioned how much better XM had gotten -- and I don't think it had changed!