I have been using the Nuvinci N360 for about a year. I suppouse all of you will get helped by my review.
The bottom line is - this is NOT a mature product, and I wouldn't recommend it at all. Furthermore, I also have a city bike with the 7-speed Shimano Nexus installed, which is a lot better.
When you buy the Nuvinci, the first thing you have to do is build a wheel. The company recommends a X2 lacing. My mechanic has built for me a X3 wheel, causing some spokes to be bend. after a while, one spoke was broken.
The efficiency is around 85%, and in the real world, what does low efficiency means? I'll tell you: It means that the pedals feel spongy...
Although the hub itself is very reliable, the peripherals that come with it are not so reliable: The hub interface and shifter are not sturdy enough.
With the Nuvinci, taking out the rear wheel for a repair outdoors is a real sore. The hub interface should be gently lifted from below. If not done this way, Then it will split and you'll find yourself collecting those 6 tiny plastic cogs from the ground. When I tried to disconnect the 2 cables myself, the cables totally messed out inside the shifter, and had to be replaced.
Conclusion: A geared hub can be very reliable. if you need one, do not buy the Nuvinci, but a non-CVT like the Shimano Nexus (or Alfine), which is:
1) Smaller (and lighter), thus is suitable for building a strong X3 lacing wheel.
2) Very easy to take out the rear wheel for repair, and needs one cable instead of two.