I've used both (NXT extensively) and NXT 2.0 for about six months now. Here is what I think...
NXT 2.0 is definitely an improvement over what was a good product to begin with. Some specific areas of concern:
Ease of application: NXT 2.0 definitely goes on easier and comes off easier. That's saying a lot because the original was pretty easy.
Post application feel: NXT 2.0 feels slightly "slicker" than the orginal.
Look: Deep, dark and very wet. (I had to detail a neighbors black accord to attest to this as my cars are white and silver - not exactly the most conducive in evaluating the look of a wax).
Long term durability: A bit better than the original, but nothing spectacular. One of my cars is a daily driver, which is NOT garage parked and exposed to the elements, the other is a recreational use vehicle which is garage parked.
I did a full job on the daily driver including a wash, clay, paint cleaning, polish and two coats of NXT 2.0 (12 hours apart) about two months ago. During that time I put about 2,000 miles on the car, including a long road trip that took me through some elements (rain) and a lot of bugs (northeast bugs, not the mammoths in the south).
Originally the car was sheeting water off like crazy. After about six weeks I noticed that it wasn't so great. I ran my finger across the paint to see if there was any wax left and it was pretty "squeeky" (indicating little or no was left). Surface tension was minimal. In other words, it was time for another coat.
My tests show on the non-garage parked daily driver, you can expect about 6 weeks (which is fine in my books) as detailing is my hobby and very therapeutic, I like getting out and waxing.
On my garage parked car, I'm on about three months with the 2.0 and it is still going strong. Gave her a wash this weekend and it is still sheeting and beading. No signs of wearing down.
HOWEVER, I should mention that I have been using the NXT Spray Wax with the garage parked car regularly during this period as Meguiars recommends this product as a "booster" for the NXT 2.0. I don't know if that has extended the life of the NXT, but I've used the spray twice in three months. I also use the ultimate quick detailer to keep the slick feel.
I've used a lot of different waxes in the 17 years I have been detailing (including Klasse, Turtle, Zymol, Zaino and Poorboys etc...) and I haven't found anything I like better (all around) than NXT 2.0, when factoring prices, performance, appearance and ease of application.
I am a big fan of the new stuff. Could it last longer? Sure, but frankly I think it does pretty well.