I have an 06 4.7 and the only thing that was wrong with it was the idle. After the first 1K miles or so it started idling roughly and you could see the RPM needle fluctuate from 450-550. I never got to take it to the dealer but it has stopped on its own and now idles at about 600 RPM. Other than that it is a great match for the vehicle. It has just enough power to move the Jeep without struggling. I have suggested it to my finds who are now looking at WKs as well.
2006 Jeep Grand Cherokee Laredo (WK) 28E
4.7 V8, Quadra-Trac II, Black Exterior, Light Khaki Interior
Upgraded: Mopar Sport Utility Crossbars
2008 Jeep Patriot Sporkt (MK) 26E
2.4L, CVVTII, 2WD, Black Exterior, Dark Gray Interior