Keep in mind, some of the complaints (from some) about the new new JGC Pentastar V6 being somewhat under powered could be coming from those who are switching from something like a V8 Tahoe or BMW X5, etc - and they may need it for towing or they have a large load with 4-passengers going up hills more so than someone who drives alone to the store and back from time to time; completely different scenarios and customers when comparing who says the V6 is underpowered; i.e. "underpowered for what?". Early on, I was on the fence too, but for any kind of heavier towing and a loaded vehicle with passengers there is no choice but the V8. Driven both several times to compare. For daily use and light duty towing, perhaps the V6 might work for most.
And, for example - anyone who use to own something like an anemic 1999/2000 4Runner with a 165hp V6 back then, the new 290hp/260ftlbs of torque for the V6 in the 2011 Jeep is a powerhouse by comparison!
Some complain about noise in the V6, perhaps that is more noticeable on takeoff, and once the vehicle stabilizes at speed, its less noticeable, whereas on the V8, it has SO MUCH TORQUE, 130lbs more, and you just don't need to mash the gas as much to get it up and going, and therefore less noise is generated on takeoffs, etc. Something only multiple comparison test drives can help one to decide for sure on either the V6 or V8. Same situation occurs when comparing something like a Honda Accord sedan I4 to the V6; the V6 is a tad smoother and quieter, but for most the I4 is plenty and you get use to it after some driving time.
Its all relative to what you are comparing to and what your real needs and uses are, where and how you plan to drive it; IMO.