I had a Nokia 610 installed in my previous A3, which I transferred to my new one in January. Small screen mounted on the corner of dash to view text messages, phone book, etc., with audio relayed through radio speakers.
When I sold the old A3 I fitted a Parrot 3100 for the guy who bought the car. Very simple install. With Symphony Radio you can route the lead for the display through the channel under the head unit, file the top of the hazard light button\coin drawer surround to feed the wire through, and then velcro the display to the bottom of the Symphony. the 3100 sits just under the cassette insert. The 3200 is probably slightly taller, so would block off the cassette insert, but who uses cassettes these days anyway.
The parrot comes with the ISO leads to relay through the radio speakers, so there's no need to buy additional cables.
Personally I prefer the Nokia, but the parrot is a more straightforward installation, and probably a bit cheaper aswell. The difficulty with the 610 is it is specific to certain phones. It has since been superceded by the 616 which works with the majority of phones.