A lot of good things have been mentioned about the power train, I'll bring up something often over-looked: the chassis of the 3rd gen was a big step up from the 2nd gen.
I have a V10 2nd gen gasser as my "bush truck", and the 3rd gen is much better in chassis stiffness, steering, braking, and NVH. It was the 1st HD pickup to use a hydroformed fully boxed chassis. Good enough they used it all the way into the 4th gen (2012). The 2013s got the upgraded chassis to boost payload and tow ratings.