From what I have heard, they downgraded the base system from what it was in the past - so it's markedly worse than normal. I'm no audiophile, but I enjoy music, and have always been disappointed by the base BMW stereos - upgrading was a must for me. The difference is *huge*.
You might try to go to your dealer to try one of each, and see for yourself. If you can, try to listen while driving on the freeway. The 328i loaner I had sounded reasonable when parked, but was awful when driving.
Past: 2011 X5 35d .... 2007 530i ..... 2002 530i ..... 1999 Honda Civic ..... 1990 Honda Accord ..... 2008 TSX