Overall, I am absolutely stoked about this ski. It takes all of the best aspects of design from previous JPs and the ARG and combines them into one. Not necessarily the best ski for me (as I have a quiver of skis), but definitely a great choice for someone who wants to charge the powder on pristine untouched days, but doesn't want to be overpowered by crud or ice a few days after the previous dump.
The JJ was by far my favorite ski that I rode at the Mission Ridge demo day. The day started off very icy and progressed to slush by the end, giving me a good feel of how the JJ would perform in most conditions. After riding skis like the EP Pro (which I love for powder), taking the JJ out was a breath of fresh air. Because of the camber underfoot along with the rockered design, the JJ gripped on the ice, blasted through crud, and yet was still very playful because of the rocker.
THe JJ took the great aspects of the ARG and last years JP Vs Julien and threw away all of the downsides. By having a solid ARG construction, camber underfoot, an actual amount of sidecut, and throwing it all together in a lightweight package, this ski killed.
I didn't buy the ski, just rode it at a demo. That being said, if you are looking for a great all mountain to powder ski, this is the one. Definitely not the best choice for everyone as a powder specific ski, but does more than get the job done.
This ski has a great flex pattern if what you are looking for is an all mountain to powder killing, rockered ski. Using the same construction as the ARG, the JP vs Julien is extremely solid and stable underfoot, while still keeping the area that is rockered relatively soft. This allows the JJ to kill it in the crud and ice, but still float great in the powder.
Again, riding this ski only a few times I cannot really comment on the durability.