I really don't know much about the Jeep Commander but, a lot depends on what your dad expects from the vehicle. He should read up on it and find out the high and low points of it. Car mags like car and driver mag and road and track cover just about everything you want to know about certain vehicles and aren't afraid to point out whats bad about them..He should also try internet reviews and comparisons..
heres a link hope this helps..
http://www.caranddriver.com/buying_guide/jeep/commander/2008_jeep_commander/2008_jeep_commander_review+type-reviews_by_make+mode-collection+id-273.html
theres also a comparison in there to a 2006 Ford Explorer Eddie Bauer 4X4..