6NR allows you to run a selection of apps in the car from the phone – things like Twitter, the Go Pro App and also the old BMW Connected App which did things like tell you remaining fuel range in the car etc etc. These apps require a cable connection to the car to function.
Connected Drive itself is a subscription service which among other things gives you access to the BMW Remote application for your Smartphone, which allows you to locate the car, lock/unlock the car, send destinations to navigation etc. For a CIC fitted car like Simon’s M3 this is £120 a year (And you get 3 years free for the first subscription, sometimes the first owner doesn’t bother, I got 3 years free on my 2010 530d even though I bought it in 2014) and also includes Realtime Traffic Information on compatible cars. It is this service, and not 6NR, that allows send to car from Google Maps.
You do not need 6NR for Connected Drive. I think 6NR is of limited benefit personally and despite having it in mine I barely use the functionality because I don’t connect my phone with a cable very often.
(BMW Recently combined the Connected and Remote apps together so there is now just one, but the above descriptions on what you can do remain the same).
Bottom line:
Is it worth paying loads of money to retrofit 6NR? Almost certainly not, perhaps if the GoPro stuff interests you maybe.
Is Connected Drive worth £120 a year? Maybe.