I did this review on fanatics a while ago, and noticed that there wasn't much talk on the Intravee on this forum, so I'm updating and copying my review here.
Cliffs Notes: If you have OEM Nav, there is no better and more reliable way to connect an iPod to our cars than the Intravee II.
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My official review appeared on page 20 of the September 2009 issue of Boston Bimmer magazine (the Boston chapter of the BMW CCA):
http://www.bigpatsfans.com/BostonBimmer.pdf