I have a 2011 Lexus ES 350 (with nav and bluetooth) and an iPhone 4S. Streaming audio over bluetooth works fine for me, as does holding down the home button to activate Siri and speak with her through the car. Unfortunately, I too am having the problem described with making phone calls from Siri, where the car's bluetooth seems to momentarily disconnect from the iPhone, causing the call to be cancelled. I can use the car's voice recognition to make the call, sure, but that involves making sure my phonebook is always sync'd, and I rather think that Siri's voice recognition works better than the car's. I'm not sure who would be at fault here, Apple or Toyota.