We have a 2010 Nissan Rogue with a CVT, and we love it. Runs great, gets great gas mileage, and we have not had one problem at all with it in 6 years and 80,000 miles. When we bought it, I was warned both by the salesman and my local mechanic that it is NOT an "offroad" vehicle, even though it sorta looks like it should be. As long as it is driven like a normal car, it is fine.
My understanding is that the lack of shifting and constant up and down of the RPMs allows engines to run much more efficiently, especially with today's computer controls.
I do think that when they get the CVT heavy duty enough to run reliably for hard use in cars and trucks for on and off road use, they will make "standard" automatics obsolete.