I plan to get the update for mine as I just purchased a used 2006 last week and I'm fairly certain it was *never* updated by the previous owner. Had to go to a martial arts tournament last weekend and the whole subdivision where the fairly new high school was located was completely missing from the maps. Had to have it navigate me to some nearby cross streets instead, lol.
EDIT: Went to the dealership this morning, they had the DVD on sale for $150. Got the 11.1 update and took me less than 5 minutes to eject the old DVD and install the new one :) Easy!