Nothing special about that model year. As any model year V6, make sure it shifts smoothly and as well as you like. There are some that get annoyed with how the eco mode robs driving pleasure. There seems to be large production tolerances. Check for wheel/tire vibrations and rattles that may annoy you, but you may need to get it up to 75 on a test drive. You have less than a 0.1% chance of a head failure, and another 0.1% of an oil leak... but there is no way to tell if the one you are looking at will fail.
There is a TSB list at WK2jeeps.com to check out for other potential problems.
The NAV updates are by DVD and cost more than $100 I think. You insert the DVD, the radio detects its an update disk and does the update. There was some discussion a few months ago about how useful the Map updates are.
I should start a sticky for used WK2 buying advice, as the forum is getting more and more questions. Any volunteers to put the first draft together?
2011 Grand Cherokee Overland V8, 2009 Liberty Rocky Mt V6, 2000 Grand Cherokee Laredo I6, 1979 CJ7 I6 Quadratrac