It's really not that hard to fit, the most time consuming thing was removing the radio cage. You have an E46 whereas I have an E39 - your job is a bit more involved as you also need to relocate the climate control panel.
I still stand by my opinion that the Windows unit is the better bet. The novelty of playing with the unit constantly will wear off - after which time it will simply become an entertainment and navigaiton system. This is why the Windows one works so well - it just.. boots into Nav every time. No faff, hassle, cheese or sauce. I'm still very happy with it.
I am led to beleive the latest units have tweaks which fix much of the irritatingly unrefined aspects of my unit - ie a new SD/USB Interface and a more responsive touchscreen.
Frankly it's still overpriced but there are few other options worth the hassle IMHO.
After 6 months, I find it's operation as a Radio/Ipod/Navigation device to be absolutely fantsatic - the unit looks great during day to day driving where its always in map mode. I have since found that the Bluetooth functionality is a bit crap, though - it's hit and miss as to whether it bothers to load my phonebook or not but otherwise generally works ok. I only really use it for incoming calls and to tell people I'll call them later and for that its fine but it's not quite a seamlessly perfect as the OEM BMW setup is for Bluetooth. Again, the newer version adds some refinements to the Bluetooth as well - it now does proper bluetooth streaming apparently for music.