The NAV system on my 2013 X3 has been good and bad, but mostly a failure.
The 3D modeling is nice in the hilly terrain of western Washington state. So, it's good when just traveling through the city and you're looking for a particular set of through streets to get from point A to point B. Integration with the HUD is really nice too and a lot safer in my opinion.
The rest is all bad. Can't speak street names. Really? About 25% of the addresses that we enter are not found (and the address has been there for many years). Therefore, we have to resort to the map app on our iPhones to get us there. Want an upgrade to the NAV database? Only every 2 years and it wil cost you (unlike my Garmins that I can update every 4 months (that have a lifetime of map updates)).