For streaming audio only, I got the Blackberry Stereo Bluetooth Gateway and it's absolutely awesome. Same straightforward setup as the Belkin you describe, but the Belkin's wiring looks better since it's self-contained and has the USB port.
My e90 has bluetooth but no wait to play music from my phone (which I use for music, podcasts, and Pandora). Since everything is contained in the armrest, everything is neatly tucked away. I just get in the car and start playing music from the phone. If a call comes in, the music stops and the car's bluetooth takes over the call. When I hang up, the music comes right back.