As previous poster stated - if you have iDrive you will notice more differences.
I successfully obtained a SW upgrade under warranty by complaining about specfic issues I knew would be fixed by the upgrade e.g.:
1) Using a programmable steering wheel button to cycle through entertainment channels would miss the Aux option
2) Navigation Pro failed to pop up direction changes in the small RH screen if the main screen was showing a non Nav display e.g. Entertainment settings.
3) Radio occasionally did not recall the station last used.
My car was made in Feb 07, I bought in May 08. The car still had the original SW.
You can tell if you have later, non original software if the iDrive main screen has a brownish colour rather than a silver colour. As previous poster says you will not notice major differences if you don't - other than maybe smoother auto changes or bluetooth reliability.
There is no way of knowing the exact version/date of the SW without dealer assistance.
e90 330d, Montego Blue, Beige Dakota Leather, Auto, Nav Pro, Bluetooth Prep, BMW Connected Drive, Voice Control, Sports Seats, Split Rear Seat, 18" Ellipsoid Wheels Style 162 Burr Walnut Trim