Finally got around to copying and pasting this from BFUK! Maybe of use to some? This was from February 2010 mind, and three cars ago, so I may not remember much if you have any questions
I've just fitted a JVC AVX77 in my 2002 330. When I was investigating it, I found forums to be most helpful, so thought I'd post my results here (even if only so people can see what certain units look like in certain cars).
See the pics below (sorry - poor photos from the phone).
Pretty happy with it overall. I was looking at a Becker Cascade, but couldn't justify the price just for the OEM look. The JVC was the plainest looking unit I could find which had the spec sheet I was looking for (was disappointed that Blaupunkt units these days look like night clubs...).
Sound is better than the original Business tape HU (I have the HK system, but the speakers are (notoriously) average). Functionality wise, it's brilliant - integrates perfectly with both iPhone and Blackberry for wireless music and calling. Steering wheel controls work too (which was a priority for me). My 60GB iTunes library lives on an iPod in the glovebox.
I went for the BMW cage/bezel as I couldn't make do with the off centre 'look'. Biggest problem was the sheer number of cables and connectors behind the unit (bloody ISO adapters!). I found the easiest thing was to mount the radio in the cage and then mount the cage in the dash - it gave better access to the rear as it was placed (centre air vents and A/C controls have to come out). I have passed the USB lead and a spare aux in through to the glove box. I want to re-route the USB to the centre arm rest, but haven't had the time yet.
It protrudes slightly further from the surround than I'd like, but I suppose that's because of the mechanism for the fold down and the touch screen. I still need to do a bit of fettling with the cage/surround as there is still a bit of alu visible along the top of the surround.
Not sure if this is of any use to anyone - feel free to ask Q's.