Map updates for the GC at $149 (does not depend on system, both use Navtec maps, link is below) is not worth the cost. Some members have updated their 2011 Maps to the most recent update, and the concensus is not worth the high cost for extremely little value. In a 2012 GC, you should already have the latest version available. I would wait at least another year or two.
I have a portable Garmin with lifetime maps and regularly check when I have issues with my 2012 GC Nav Maps, and have never found the most recent maps to be any different/better. Most of the maps are at least 1-2 years out of date on the day they are issued, in my opinion.
The forum search function works great to check before posting, this has been covered a number of times recently.