Just bought an 05 4.4i Sport w/ 106k on it and just did this... and though the screen no longer has those big dead spots that these are prone to. The replacement Sharp screen does not look as good from the driver seat as the original. The actual process is super simple though.

From my driving position (I'm 6'8") I can barely see what is on the screen, especially in bright sunlight. I don't know if the screens have the wrong viewing angle, or contrast, or what... but they do not look as good as the OEM... at least in my case. I used the Sharp part number from that link above. From straight on, looks fine. YMMV.

Is there a hidden menu or something in these head units to adjust contrast? Being familiar with BMW's (own 4 currently, 13ish total) I know they frequently put hidden menus in their electronics.

EDIT: Replacement screen cost $125 shipped. Easy job. After doing the repair though, the wife and I talked about it and are going to go with the Avin Avant 2 so we can add some more modern technologies to the cabin.