I have a 2013 M37 and love it! Only have the premium package, no tech or sport package.
The differences I am aware of in the 2013 over the 2011-2012 are:
Rear sonar - not sure if this could be optioned into a 2011-2012 but I know the base and premium packages at least did not have it. all 2013+ models have it
Infiniti Connection - (SOS button by the sunroof buttons and Infiniti connection options on the nav). This is a paid subscription similar to onStar (
http://www.motorwerksinfiniti.com/infiniti-connection/). However the system uses GSM-based 2G provided by AT&T. AT&T already announced they are shutting off 2G at the end of 2016 so this Infiniti connection system may be useless after this date anyway. Infiniti has offered no word on any update plans but they do mention AT&T cutoff for this service as Dec 31, 2016. the odd thing is they are still selling infiniti connection with 2G on the 2015 models too. So they are selling a service with a known expiration date of less than 2 years.
Automatic latch for the trunk - softly set trunk lid down and trunk latch automatically pulls it fully shut
Auto-dimming side mirrors.
New updated microphone for bluetooth phone calling. This is actually updateable at the delear via a TSB (ITB11047) on 2011--2012 models but the 2013+ models have the new microphone by default
There may be others but those are some of the differences I know of