Was at a buddy's place and he's a Motortrend subscriber. Just read the review they did on the JK Rubicon in the latest, Oct. 2006 edition of the magazine.
Review is set in Africa and was a DC arranged deal, apparently (it's kind of like, "look, just take a Rubicon JK to Moab or wherever -- a place it might be used with some regularity -- and cut loose." But, DC wanted to do it in Africa). Anyway, they gave the JK high reviews all around, except for a couple of issues where front seat passengers were banging their arms on the door plastic over bumps or something and, when top up, the JKs lack of an exposed roll-bar to grip when driving over obstacles. Another issue was off-the-line acceleration was a bit muted vs. the 4.0L TJ due to increased JK weight (nah!?). No numbers on real-world mileage, but claimed figures are 17/19
Stiffness of the new boxed frame was highly praised (didn't know that of theTJs/YJs/CJs was too shabby?). 4" of increased width vs. TJ/YJ was a bit of an issue on some terrain, a TJ driver in the group having an easier time threading the needle through a squeeze-type trail segment. Power windowed/locked doors are removable, just detach an electrical connection on the door. A driver in the review apparently rolled one of the JK rubicons and it was pushed back over, mechanically checked and continued to drive ok.
Overall, it seems like the Rubicon JK is a fairly decent ride, according to Motortrend. To me, it seems like the DC people put even more thought in to the JK than they did the TJ, almost like the Daimler people are getting less cautious about influencing the design, maybe for the better (new G-Wagon stiff boxed frame, "commanding" width increase). Does seem like there aren't going to be many aftermarket Jeep ads that read, "you know the weak factory "X" part on the JK? Buy our super tough replacement." But, I could be wrong.